Topic Editors

Dr. Francesca Raganati
Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università degli Studi di Napoli Federico II, Piazzale Tecchio 80, 80125 Napoli, Italy
Dr. Alessandra Procentese
Department on Industrial Engineering, University of Salerno "UNISA", Via Giovanni Paolo II, 132, 4084 Fisciano - Salerno, Italy

Bioreactors: Control, Optimization and Applications

Abstract submission deadline
closed (31 October 2022)
Manuscript submission deadline
closed (31 December 2022)
Viewed by
59323

Topic Information

Dear Colleagues,

Biochemical engineering deals with the processing of biological or chemical materials using enzymes or living cells as biological catalysts. At a central position in a biotechnological process is the bioreactor. Its role is frequently dominant on the overall technical and economical performance of the process. The characteristics of the biological reaction can also affect the requirements on the other steps of the process, such as the preparation of the media and the downstream operations for product recovery and purification.

Each bioconversion process is dependent on many factors including growth conditions, homogeneity of fermentation medium, cell density, etc. The decisions made in the design of bioreactors might have a significant impact on the overall process performance; in fact, bioreactor design/operation mode is an important key factor to achieve optimum conditions for maximum yield/productivity in fermentation; the main function of a properly designed bioreactor is to provide a controlled environment to achieve optimal growth and/or product formation in the particular cell system employed. In this regard, knowledge of reaction kinetics is essential to gain an understanding of the workings of a biological reactor. Other areas of bioprocess engineering, such as mass and energy balances, mixing, mass transfer, and heat transfer, are also required.

Moreover, qualitative and quantitative descriptions of a production process through the analysis of various parameters by automatic or manual methods are necessary for process control and optimization. The objects of process monitoring can be the environmental status or the varied values of operational variables. Through analysis, the cellular or engineering problems of a bioreactor on different scales can be identified. Inter-scale observation and operation are crucial in bioprocess optimization.

In this context, there is the necessity to research and improve the topic “Bioreactors: Control, Optimization and Applications”. The objective of this Topic Project is to showcase the diversity and advances in research that contributes to developing effective systems for the microorganism culture and bio-chemical production.

Original papers are solicited on experimental/theoretical studies on bioreactor systems. We are particularly interested in receiving manuscripts that integrate biology and engineering research and/or experimental and theoretical studies. We invite researchers from all areas of bioengineering to submit manuscripts for this important Topic Project.

Dr. Francesca Raganati
Dr. Alessandra Procentese
Topic Editors

Keywords

  • cell culture
  • fermentation
  • bioprocessing
  • scale-up
  • bioreactor design
  • mathematical models
  • monitoring and control
  • bioreactor optimization

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Processes
processes
3.352 3.5 2013 12.7 Days 2000 CHF
Catalysts
catalysts
4.501 5.5 2011 12.7 Days 2200 CHF
Applied Sciences
applsci
2.838 3.7 2011 14.9 Days 2300 CHF
Fermentation
fermentation
5.123 5.3 2015 13.4 Days 2000 CHF
Bioengineering
bioengineering
5.046 6.3 2014 14.8 Days 2000 CHF

Preprints is a platform dedicated to making early versions of research outputs permanently available and citable. MDPI journals allow posting on preprint servers such as Preprints.org prior to publication. For more details about reprints, please visit https://www.preprints.org.

Published Papers (45 papers)

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Article
Online Process State Estimation for Hansenula Polymorpha Cultivation with 2D Fluorescence Spectra-Based Chemometric Model Calibrated from a Theoretical Model in Place of Offline Measurements
Fermentation 2023, 9(2), 95; https://doi.org/10.3390/fermentation9020095 - 21 Jan 2023
Viewed by 211
Abstract
The use of 2D fluorescence spectra is a powerful, instantaneous, and highly accurate method to estimate the state of bioprocesses. The conventional approach for calibrating a chemometric model from raw spectra needs a large number of offline measurements from numerous runs, which is [...] Read more.
The use of 2D fluorescence spectra is a powerful, instantaneous, and highly accurate method to estimate the state of bioprocesses. The conventional approach for calibrating a chemometric model from raw spectra needs a large number of offline measurements from numerous runs, which is tedious, time-consuming, and error-prone. In addition, many process variables lack direct signal responses, which forces chemometric models to make predictions based on indirect responses. In order to predict glycerol and biomass concentrations online in batch cultivation of Hansenula polymorpha, this study substituted offline measurements with simulated values. The only data from cultivations needed to generate the chemometric model were the 2D fluorescence spectra, with the presumption that they contain sufficient information to characterize the process state at a measurement point. The remainder of the evaluation was carried out with the aid of a mathematical process model that describes the theoretical interferences between process variables in the system. It is shown that the process model parameters, including microbial growth rate, the yield of biomass from glycerol, and lag time can be determined from only the spectra by employing a model-based calibration (MBC) approach. The prediction errors for glycerol and biomass concentrations were 8.6% and 5.7%, respectively. An improved model-based calibration (IMBC) approach is presented that calibrates a chemometric model for only biomass. Biomass was predicted from a 2D fluorescence spectrum in new cultivations, and glycerol concentration was estimated from the process model utilizing predicted biomass as an input. By using this method, the prediction errors for glycerol and biomass were reduced to 5.2% and 4.7%, respectively. The findings indicate that model-based calibration, which can be carried out with only 2D fluorescence spectra gathered from prior runs, is an effective method for estimating the process state online. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
Article
A Two-Compartment Fermentation System to Quantify Strain-Specific Interactions in Microbial Co-Cultures
Bioengineering 2023, 10(1), 103; https://doi.org/10.3390/bioengineering10010103 - 11 Jan 2023
Viewed by 432
Abstract
To fulfil the growing interest in investigating microbial interactions in co-cultures, a novel two-compartment bioreactor system was developed, characterised, and implemented. The system allowed for the exchange of amino acids and peptides via a polyethersulfone membrane that retained biomass. Further system characterisation revealed [...] Read more.
To fulfil the growing interest in investigating microbial interactions in co-cultures, a novel two-compartment bioreactor system was developed, characterised, and implemented. The system allowed for the exchange of amino acids and peptides via a polyethersulfone membrane that retained biomass. Further system characterisation revealed a Bodenstein number of 18, which hints at backmixing. Together with other physical settings, the existence of unwanted inner-compartment substrate gradients could be ruled out. Furthermore, the study of Damkoehler numbers indicated that a proper metabolite supply between compartments was enabled. Implementing the two-compartment system (2cs) for growing Streptococcus thermophilus and Lactobacillus delbrueckii subs. bulgaricus, which are microorganisms commonly used in yogurt starter cultures, revealed only a small variance between the one-compartment and two-compartment approaches. The 2cs enabled the quantification of the strain-specific production and consumption rates of amino acids in an interacting S. thermophilusL. bulgaricus co-culture. Therefore, comparisons between mono- and co-culture performance could be achieved. Both species produce and release amino acids. Only alanine was produced de novo from glucose through potential transaminase activity by L. bulgaricus and consumed by S. thermophilus. Arginine availability in peptides was limited to S. thermophilus’ growth, indicating active biosynthesis and dependency on the proteolytic activity of L. bulgaricus. The application of the 2cs not only opens the door for the quantification of exchange fluxes between microbes but also enables continuous production modes, for example, for targeted evolution studies. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
(This article belongs to the Section Biochemical Engineering)
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Article
Advanced Monitoring and Control of Redox Potential in Wine Fermentation across Scales
Fermentation 2023, 9(1), 7; https://doi.org/10.3390/fermentation9010007 - 22 Dec 2022
Viewed by 503
Abstract
Combined with real-time monitoring of density and temperature, the control of the redox potential provides a new approach to influencing cell metabolism during growth, cell viability and non-growing yeast activity in wine fermentations. Prior research indicates that the problem of sluggish and incomplete [...] Read more.
Combined with real-time monitoring of density and temperature, the control of the redox potential provides a new approach to influencing cell metabolism during growth, cell viability and non-growing yeast activity in wine fermentations. Prior research indicates that the problem of sluggish and incomplete fermentation can be alleviated by maintaining a constant redox potential during the ethanol fermentation. A secondary trait of hydrogen sulfide formation from elemental sulfur also seems to be associated with the development of low redox potentials during fermentation and this might be prevented by the deliberate control of redox potentials in a certain range. While the control of the redox potential during wine fermentations has been demonstrated previously at the research scale (100 L), the ability to control it in larger volumes typically seen in commercial conditions remained unanswered. Wine fermentations from the same load of Cabernet Sauvignon grapes from the 2021 harvest were conducted at three volumes: 100 L and 1500 L in a research winery and 10,000 L in a commercial winery. Using only pulses of air delivery, the redox potential was successfully controlled to −40 mV referenced to a silver/silver chloride electrode throughout the fermentations, at all scales. This appears to be the first published result of a controlled fermentation trial that includes the commercial scale and demonstrates the scalability of control of redox potential in wine fermentations. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
A Comprehensive Mechanistic Yeast Model Able to Switch Metabolism According to Growth Conditions
Fermentation 2022, 8(12), 710; https://doi.org/10.3390/fermentation8120710 - 06 Dec 2022
Viewed by 561
Abstract
This paper proposes a general approach for building a mechanistic yeast model able to predict the shift of metabolic pathways. The mechanistic model accounts for the coexistence of several metabolic pathways (aerobic fermentation, glucose respiration, anaerobic fermentation and ethanol respiration) whose activation depends [...] Read more.
This paper proposes a general approach for building a mechanistic yeast model able to predict the shift of metabolic pathways. The mechanistic model accounts for the coexistence of several metabolic pathways (aerobic fermentation, glucose respiration, anaerobic fermentation and ethanol respiration) whose activation depends on growth conditions. This general approach is applied to a commercial strain of Saccharomyces cerevisiae. Stoichiometry and yeast kinetics were mostly determined from aerobic and completely anaerobic experiments. Known parameters were taken from the literature, and the remaining parameters were estimated by inverse analysis using the particle swarm optimization method. The optimized set of parameters allows the concentrations to be accurately determined over time, reporting global mean relative errors for all variables of less than 7 and 11% under completely anaerobic and aerobic conditions, respectively. Different affinities of yeast for glucose and ethanol tolerance under aerobic and anaerobic conditions were obtained. Finally, the model was successfully validated by simulating a different experiment, a batch fermentation process without gas injection, with an overall mean relative error of 7%. This model represents a useful tool for the control and optimization of yeast fermentation systems. More generally, the modeling framework proposed here is intended to be used as a building block of a digital twin of any bioproduction process. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Communication
A Critical Remark on the Applications of Gas-Phase Biofilter (Packed-Bed Bioreactor) Models in Aqueous Systems
Bioengineering 2022, 9(11), 657; https://doi.org/10.3390/bioengineering9110657 - 05 Nov 2022
Viewed by 487
Abstract
The principles of gas-phase biofilter systems, modeling, and operations are quite different from liquid-phase biofilter systems. Because of “biofilter” terminology used in both gas and liquid-phase systems, researchers often mistakenly use gas-phase models in liquid-phase applications for the analysis of data and determining [...] Read more.
The principles of gas-phase biofilter systems, modeling, and operations are quite different from liquid-phase biofilter systems. Because of “biofilter” terminology used in both gas and liquid-phase systems, researchers often mistakenly use gas-phase models in liquid-phase applications for the analysis of data and determining kinetic parameters. For example, recent studies show a well-known gas-phase biofilter model, known as Ottengraf–Van Den Oever zero-order diffusion-limited model, is applied for analysis of experimental data from an aqueous biofilter system which is used for the removal of toxic divalent copper [Cu(II)] and chromium (VI). The objective of this research is to present the limitations and principles of gas-phase biofilter models and to highlight the incorrect use of gas-phase biofilter models in liquid-phase systems that can lead to erroneous results. The outcome of this work will facilitate scientists and engineers in distinguishing two different systems and selecting a more suitable biofilter model for the analysis of experimental data in determining kinetic parameters. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Communication
Highly Efficient Synthesis of Cinnamamides from Methyl Cinnamates and Phenylethylamines Catalyzed by Lipozyme® TL IM under Continuous-Flow Microreactors
Catalysts 2022, 12(10), 1265; https://doi.org/10.3390/catal12101265 - 18 Oct 2022
Viewed by 628
Abstract
While a few derivatives of cinnamamides exhibited anti-inflammatory and/ or analgesic activity, in this study, we developed a highly efficient method for the synthesis of cinnamamides from methyl cinnamates and phenylethylamines catalyzed by Lipozyme® TL IM in continuous-flow microreactors. The reaction parameters [...] Read more.
While a few derivatives of cinnamamides exhibited anti-inflammatory and/ or analgesic activity, in this study, we developed a highly efficient method for the synthesis of cinnamamides from methyl cinnamates and phenylethylamines catalyzed by Lipozyme® TL IM in continuous-flow microreactors. The reaction parameters and broad substrate range of the new method was studied. Maximum conversion (91.3%) was obtained under the optimal condition of substrate molar ratio of 1:2 (methyl 4-chlorocinnamate: phenylethylamine) at 45 °C for about 40 min. The remarkable features of this work include short residence time, mild reaction conditions, easy control of the reaction process, and that the catalyst can be recycled or reused, which provide a rapid and economical strategy for the synthesis and design of cinnamamide derivatives for further research on drug activity. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Comparative Analysis of a Family of Sliding Mode Observers under Real-Time Conditions for the Monitoring in the Bioethanol Production
Fermentation 2022, 8(9), 446; https://doi.org/10.3390/fermentation8090446 - 07 Sep 2022
Viewed by 742
Abstract
Online monitoring of fermentation processes is a necessary task to determine concentrations of key biochemical compounds, diagnose faults in process operations, and implement feedback controllers. However, obtaining the signals of all-important variables in a real process is a task that may be difficult [...] Read more.
Online monitoring of fermentation processes is a necessary task to determine concentrations of key biochemical compounds, diagnose faults in process operations, and implement feedback controllers. However, obtaining the signals of all-important variables in a real process is a task that may be difficult and expensive due to the lack of adequate sensors, or simply because some variables cannot be directly measured. From the above, a model-based approach such as state observers may be a viable alternative to solve the estimation problem. This work shows a comparative analysis of the real-time performance of a family of sliding-mode observers for reconstructing key variables in a batch bioreactor for fermentative ethanol production. These observers were selected for their robust performance under model uncertainties and finite-time estimation convergence. The selected sliding-mode observers were the first-order sliding mode observer, the proportional sliding mode observer, and the high-order sliding mode observer. For estimation purposes, a power law kinetic model for ethanol production by Saccharomyces cerevisiae was performed. A hybrid methodology allows the kinetic parameters to be adjusted, and an approach based on inference diagrams allows the observability of the model to be determined. The experimental results reported here show that the observers under analysis were robust to modeling errors and measurement noise. Moreover, the proportional sliding-mode observer was the algorithm that exhibited the best performance. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Enhanced Production Process of Recombinant Mature Serratiopeptidase in Escherichia coli Using Fed-Batch Culture by Self-Proteolytic Activity of Fusion Protein
Fermentation 2022, 8(7), 307; https://doi.org/10.3390/fermentation8070307 - 29 Jun 2022
Cited by 2 | Viewed by 1253
Abstract
Microbial enzymes are increasingly finding applications as therapeutics due to their targeted activity and minimal side effects. Serratiopeptidase, also known as a miracle enzyme, has already proved its potential as an anti-inflammatory, mucolytic, fibrinolytic, analgesic in many studies. A cost effective, bioreactor level [...] Read more.
Microbial enzymes are increasingly finding applications as therapeutics due to their targeted activity and minimal side effects. Serratiopeptidase, also known as a miracle enzyme, has already proved its potential as an anti-inflammatory, mucolytic, fibrinolytic, analgesic in many studies. A cost effective, bioreactor level production process has been described here comprising of the fed-batch fermentation to produce recombinant serratiopeptidase protein expressed as a fusion construct. High yield of cell mass as well as protein was obtained by the optimization of bioreactor parameters. The downstream solubilization and purification processes were also optimized to achieve maximum yield of pure, active serratiopeptidase protein. A final yield of 2.5 ± 0.764 g L−1 of protein was obtained, having 8382 ± 291 U mg−1 of specific caseinolytic activity. Additionally, a novel, unexpected self-proteolytic activity of the enzyme that cleaves the N-terminal 6× His-SUMO fusion tag along with the enzyme propeptide, thus yielding a mature serratiopeptidase, was also found. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Review
Pasteurellosis Vaccine Commercialization: Physiochemical Factors for Optimum Production
Processes 2022, 10(7), 1248; https://doi.org/10.3390/pr10071248 - 23 Jun 2022
Viewed by 1041
Abstract
Pasteurella spp. are Gram-negative facultative bacteria that cause severe economic and animal losses. Pasteurella-based vaccines are the most promising solution for controlling Pasteurella spp. outbreaks. Remarkably, insufficient biomass cultivation (low cell viability and productivity) and lack of knowledge about the cultivation process [...] Read more.
Pasteurella spp. are Gram-negative facultative bacteria that cause severe economic and animal losses. Pasteurella-based vaccines are the most promising solution for controlling Pasteurella spp. outbreaks. Remarkably, insufficient biomass cultivation (low cell viability and productivity) and lack of knowledge about the cultivation process have impacted the bulk production of animal vaccines. Bioprocess optimization in the shake flask and bioreactor is required to improve process efficiency while lowering production costs. However, its state of the art is limited in providing insights on its biomass upscaling, preventing a cost-effective vaccine with mass-produced bacteria from being developed. In general, in the optimum cultivation of Pasteurella spp., production factors such as pH (6.0–8.2), agitation speed (90–500 rpm), and temperature (35–40 °C) are used to improve production yield. Hence, this review discusses the production strategy of Pasteurella and Mannheimia species that can potentially be used in the vaccines for controlling pasteurellosis. The physicochemical factors related to operational parameter process conditions from a bioprocess engineering perspective that maximize yields with minimized production cost are also covered, with the expectation of facilitating the commercialization process. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Synergistic Inorganic Carbon and Denitrification Genes Contributed to Nitrite Accumulation in a Hydrogen-Based Membrane Biofilm Reactor
Bioengineering 2022, 9(5), 222; https://doi.org/10.3390/bioengineering9050222 - 20 May 2022
Cited by 4 | Viewed by 1253
Abstract
Partial denitrification, the termination of NO3-N reduction at nitrite (NO2-N), has received growing interest for treating wastewaters with high ammonium concentrations, because it can be coupled to anammox for total-nitrogen removal. NO2 accumulation in the [...] Read more.
Partial denitrification, the termination of NO3-N reduction at nitrite (NO2-N), has received growing interest for treating wastewaters with high ammonium concentrations, because it can be coupled to anammox for total-nitrogen removal. NO2 accumulation in the hydrogen (H2)-based membrane biofilm reactor (MBfR) has rarely been studied, and the mechanisms behind its accumulation have not been defined. This study aimed at achieving the partial denitrification with H2-based autotrophic reducing bacteria in a MBfR. Results showed that by increasing the NO3 loading, increasing the pH, and decreasing the inorganic-carbon concentration, a nitrite transformation rate higher than 68% was achieved. Community analysis indicated that Thauera and Azoarcus became the dominant genera when partial denitrification was occurring. Functional genes abundances proved that partial denitrification to accumulate NO2 was correlated to increases of gene for the form I RuBisCo enzyme (cbbL). This study confirmed the feasibility of autotrophic partial denitrification formed in the MBfR, and revealed the inorganic carbon mechanism in MBfR denitrification. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Real-Time Optimization of Wastewater Treatment Plants via Constraint Adaptation
Processes 2022, 10(5), 990; https://doi.org/10.3390/pr10050990 - 17 May 2022
Cited by 1 | Viewed by 878
Abstract
An important requirement of wastewater treatment plants (WWTPs) is compliance with the local regulations on effluent discharge, which are going to become more stringent in the future. The operation of WWTPs exhibits a trade-off between operational cost and effluent quality, which provides a [...] Read more.
An important requirement of wastewater treatment plants (WWTPs) is compliance with the local regulations on effluent discharge, which are going to become more stringent in the future. The operation of WWTPs exhibits a trade-off between operational cost and effluent quality, which provides a scope for optimization. Process optimization is usually done by optimizing a model of the process. However, due to inevitable plant–model mismatch, the computed optimal solution is usually not optimal for the plant. This study represents the first attempt to handle plant–model mismatch via constraint adaptation (CA) for the real-time optimization of WWTPs. In this simulation study, the “plant” is a model adopted from the BSM1 benchmark, while a reduced-order “model” is used for making predictions and computing the optimal inputs. A first implementation uses steady-state measurements of the plant constraints to adjust the model in the optimization framework. A fast CA technique is also proposed, which adjusts the model using transient measurements. It is observed that, even in the presence of significant plant–model mismatch, the two proposed techniques are able to meet the active plant constraints. These techniques are found to reduce the pumping and aeration energy by 20%, as compared to that adopted in BSM1. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Influence of Operating Conditions on Reuterin Production Using Resting Cells of Limosilactobacillus reuteri DPC16
Fermentation 2022, 8(5), 227; https://doi.org/10.3390/fermentation8050227 - 16 May 2022
Viewed by 1116
Abstract
Limosilactobacillus reuteri strains can secrete a potentially valuable chemical and broad-spectrum antimicrobial substance named reuterin (3-hydroxypropionaldehyde, 3-HPA). L. reuteri DPC16 is a novel and patented probiotic strain that is used commercially because of its proven ability to kill various foodborne pathogens. A two-step [...] Read more.
Limosilactobacillus reuteri strains can secrete a potentially valuable chemical and broad-spectrum antimicrobial substance named reuterin (3-hydroxypropionaldehyde, 3-HPA). L. reuteri DPC16 is a novel and patented probiotic strain that is used commercially because of its proven ability to kill various foodborne pathogens. A two-step process has been developed for reuterin production from glycerol using L. reuteri DPC16. Cells were grown, followed by harvesting, and then were incubated with glycerol for reuterin production. Parameters investigated during the glycerol conversion included the initial glycerol concentration, the biomass concentration, pH, culture age at harvesting, conversion time, and temperature. The highest reuterin yield was obtained using 21 g/L 24 h old cells, to convert glycerol solution (300 mmol/L) in 1 h at 30 °C and pH 6.2. The most efficient transformation of glycerol to reuterin was achieved in approximately 20 h of growth of cells at 25 °C and pH 6.8. Using the regression equation of this study, the maximum concentration of reuterin can be obtained using 25 g/L 20 h old DPC6 cells to ferment 350 mmol/L glycerol (initial concentration) for 2 h at 25 °C and pH 6.8 The ranking of effects on reuterin production for the six single factors was glycerol concentration > pH > conversion time > biomass concentration > temperature > culture age. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Effectiveness of Low-Cost Bioreactors Integrated with a Gas Stripping System for Butanol Fermentation from Sugarcane Molasses by Clostridium beijerinckii
Fermentation 2022, 8(5), 214; https://doi.org/10.3390/fermentation8050214 - 08 May 2022
Cited by 1 | Viewed by 1191
Abstract
The effectiveness of column bioreactors for butanol fermentation from sugarcane molasses by Clostridium beijerinckii TISTR 1461 was investigated. This fermentation was operated at an initial pH of 6.5 and temperature of 37 °C under anaerobic conditions. A 1-L bubble column bioreactor was used [...] Read more.
The effectiveness of column bioreactors for butanol fermentation from sugarcane molasses by Clostridium beijerinckii TISTR 1461 was investigated. This fermentation was operated at an initial pH of 6.5 and temperature of 37 °C under anaerobic conditions. A 1-L bubble column bioreactor was used with various gas circulation rates ranging from 0.2 to 1.0 L/min. The highest butanol concentration (PB, 8.72 g/L), productivity (QB, 0.24 g/L∙h) and yield (YB/S, 0.21 g/g) were obtained with a gas circulation of 0.2 L/min. To improve butanol production efficiency, gas-lift column bioreactors with internal and external loops at 0.2 L/min of circulating gas were used. Higher PB (10.50–10.58 g/L), QB (0.29 g/L∙h) and YB/S (0.22–0.23 g/g) values were obtained in gas-lift column bioreactors. These values were similar to those using a more complex 2-L stirred-tank bioreactor (PB, 10.10 g/L; QB, 0.28 g/L h and YB/S, 0.22 g/g). Hence, gas-lift column bioreactors have potential for use as low-cost fermenters instead of stirred-tank bioreactors for butanol fermentation. When the gas-lift column bioreactor with an internal loop was coupled with a gas stripping system, it yielded an enhanced PB and sugar consumption of approximately 9% and 7%, respectively, compared to a system with no gas stripping. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Automatic Programmable Bioreactor with pH Monitoring System for Tissue Engineering Application
Bioengineering 2022, 9(5), 187; https://doi.org/10.3390/bioengineering9050187 - 25 Apr 2022
Cited by 1 | Viewed by 1737
Abstract
Tissue engineering technology has been advanced and applied to various applications in the past few years. The presence of a bioreactor is one key factor to the successful development of advanced tissue engineering products. In this work, we developed a programmable bioreactor with [...] Read more.
Tissue engineering technology has been advanced and applied to various applications in the past few years. The presence of a bioreactor is one key factor to the successful development of advanced tissue engineering products. In this work, we developed a programmable bioreactor with a controlling program that allowed each component to be automatically operated. Moreover, we developed a new pH sensor for non-contact and real-time pH monitoring. We demonstrated that the prototype bioreactor could facilitate automatic cell culture of L929 cells. It showed that the cell viability was greater than 80% and cell proliferation was enhanced compared to that of the control obtained by a conventional cell culture procedure. This result suggests the possibility of a system that could be potentially useful for medical and industrial applications, including cultured meat, drug testing, etc. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Targeting on Different Characteristic Continuous Variables in Process Transition for Ethylene Column with Wide-Range Feed Fluctuation
Processes 2022, 10(4), 796; https://doi.org/10.3390/pr10040796 - 18 Apr 2022
Cited by 1 | Viewed by 636
Abstract
For the study of the transition strategies of continuous chemical processes, both continuity and dynamic characteristics in the physical sense are critical. The continuous transition strategy has a higher information density and can describe the real situation as closely as possible. In addition, [...] Read more.
For the study of the transition strategies of continuous chemical processes, both continuity and dynamic characteristics in the physical sense are critical. The continuous transition strategy has a higher information density and can describe the real situation as closely as possible. In addition, the accuracy of the dynamic characteristics is necessary because the process transition is the study of the dynamic system processes. However, existing transition strategies have certain shortcomings. Dynamic optimization can obtain transition strategies with different characteristics but no physical meaning and a frequency domain-based analytical approach can acquire a continuous transition strategy with physical meaning, but its dynamic characteristics are the same. Therefore, by integrating the advantages of the existing strategies, a new transition strategy has been presented, which possesses different dynamic characteristics and continuity synchronous with physical significance. When process transition occurs, the proposed strategy results in less fluctuation and can quickly reach and maintain a steady state. Furthermore, the strategy is also suitable for the rapid application of different transition processes in the same plant. The performance of the transition strategies is evaluated through research on a continuous feed ethylene column. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Enhanced Phenazine-1-Carboxamide Production in Pseudomonas chlororaphis H5△fleQrelA through Fermentation Optimization
Fermentation 2022, 8(4), 188; https://doi.org/10.3390/fermentation8040188 - 18 Apr 2022
Viewed by 1233
Abstract
Phenazine-1-carboxamide (PCN) is effective to control many plant pathogens, and improving PCN production would be of great significance in promoting its development as a biopesticide. This study was conducted to improve the PCN production of Pseudomonas chlororaphis H5△fleQrelA through fermentation [...] Read more.
Phenazine-1-carboxamide (PCN) is effective to control many plant pathogens, and improving PCN production would be of great significance in promoting its development as a biopesticide. This study was conducted to improve the PCN production of Pseudomonas chlororaphis H5△fleQrelA through fermentation optimization in both shake flask and bioreactor. The PCN production of H5△fleQrelA was improved from 2.75 ± 0.23 g/L to 5.51 ± 0.17 g/L by medium optimization in shake flask using Plackett-Burman design, the path of steepest ascent experiment and central composite design. Then, PCN production reached 8.58 ± 0.25 g/L through optimizing pH in 1 L bioreactor. After pH optimization, the transcriptional levels of ccoO_2 and ccoQ_2 genes related to microbial aerobic respiration were significantly upregulated, and the relative abundance of 3-oxo-C14-HSL was significantly enhanced 15-fold, and these changes were vital for cell activity and metabolites production. Furthermore, the PCN production reached 9.58 ± 0.57 g/L after optimization of the fed-batch fermentation strategy in 1 L bioreactor. Finally, the fermentation scale-up of the optimal medium and optimal feeding strategy were conducted in 30 L bioreactor at the optimal pH, and their PCN production reached 9.17 g/L and 9.62 g/L respectively, which were comparable to that in 1 L bioreactor. In this study, the high PCN production was achieved from the shake-flask fermentation to 30 L bioreactor, and the optimal feeding strategy improved PCN production in bioreactor without increasing total glycerol compared with in shake flask. It provides promising pathways for the optimization of processes for the production of other phenazines. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Improved Titer in Late-Stage Mammalian Cell Culture Manufacturing by Re-Cloning
Bioengineering 2022, 9(4), 173; https://doi.org/10.3390/bioengineering9040173 - 15 Apr 2022
Cited by 1 | Viewed by 1715
Abstract
Improving productivity to reduce the cost of biologics manufacturing and ensure that therapeutics can reach more patients remains a major challenge faced by the biopharmaceutical industry. Chinese hamster ovary (CHO) cell lines are commonly prepared for biomanufacturing by single cell cloning post-transfection and [...] Read more.
Improving productivity to reduce the cost of biologics manufacturing and ensure that therapeutics can reach more patients remains a major challenge faced by the biopharmaceutical industry. Chinese hamster ovary (CHO) cell lines are commonly prepared for biomanufacturing by single cell cloning post-transfection and recovery, followed by lead clone screening, generation of a research cell bank (RCB), cell culture process development, and manufacturing of a master cell bank (MCB) to be used in early phase clinical manufacturing. In this study, it was found that an additional round of cloning and clone selection from an established monoclonal RCB or MCB (i.e., re-cloning) significantly improved titer for multiple late phase monoclonal antibody upstream processes. Quality attributes remained comparable between the processes using the parental clones and the re-clones. For two CHO cells expressing different antibodies, the re-clone performance was successfully scaled up at 500-L or at 2000-L bioreactor scales, demonstrating for the first time that the re-clone is suitable for late phase and commercial manufacturing processes for improvement of titer while maintaining comparable product quality to the early phase process. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Enhancement of PHA Production by a Mixed Microbial Culture Using VFA Obtained from the Fermentation of Wastewater from Yeast Industry
Fermentation 2022, 8(4), 180; https://doi.org/10.3390/fermentation8040180 - 11 Apr 2022
Cited by 6 | Viewed by 2417
Abstract
Wastewater from the yeast production industry (WWY) is potentially harmful to surface water due to its high nitrogen and organic matter content; it can be used to produce compounds of higher commercial value, such as polyhydroxyalkanoates (PHA). PHA are polyester-type biopolymers synthesized by [...] Read more.
Wastewater from the yeast production industry (WWY) is potentially harmful to surface water due to its high nitrogen and organic matter content; it can be used to produce compounds of higher commercial value, such as polyhydroxyalkanoates (PHA). PHA are polyester-type biopolymers synthesized by bacteria as energy reservoirs that can potentially substitute petrochemical-derived plastics. In this exploratory work, effluent from WWY was used to produce PHA, using a three-step setup of mixed microbial cultures involving one anaerobic and two aerobic reactors. First, volatile fatty acids (VFA; 2.5 g/L) were produced on an anaerobic batch reactor (reactor A) fed with WWY, using a heat pretreated sludge inoculum to eliminate methanogenic activity. Concurrently, PHA-producing bacteria were enriched using synthetic VFA in a sequencing batch reactor (SBR, reactor C) operated for 78 days. Finally, a polyhydroxybutyrate (PHB)-producing reactor (reactor B) was assembled using the inoculum enriched with PHA-producing bacteria and the raw and distilled effluent from the anaerobic reactor as a substrate. A maximum accumulation of 17% of PHB based on cell dry weight was achieved with a yield of 1.2 g PHB/L when feeding with the distilled effluent. Roche 454 16S rRNA gene amplicon pyrosequencing of the PHA-producing reactor showed that the microbial community was dominated by the PHA-producing bacterial species Paracoccus alcalophilus (32%) and Azoarcus sp. (44%). Our results show promising PHB accumulation rates that outperform previously reported results obtained with real substrates and mixed cultures, demonstrating a sustainable approach for the production of PHA less prone to contamination than a pure culture. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Enhancing the Productivity and Stability of Superoxide Dismutase from Saccharomyces cerevisiae TBRC657 and Its Application as a Free Radical Scavenger
Fermentation 2022, 8(4), 169; https://doi.org/10.3390/fermentation8040169 - 06 Apr 2022
Cited by 1 | Viewed by 1197
Abstract
Superoxide dismutase (SOD) is crucial antioxidant enzyme that plays a role in protecting cells against harmful reactive oxygen species (ROS) which are generated inside cells. Due to its functionality, SOD is used in many applications. In this study, Saccharomyces cerevisiae TBRC657 was selected [...] Read more.
Superoxide dismutase (SOD) is crucial antioxidant enzyme that plays a role in protecting cells against harmful reactive oxygen species (ROS) which are generated inside cells. Due to its functionality, SOD is used in many applications. In this study, Saccharomyces cerevisiae TBRC657 was selected as the SOD producer due to its high SOD production. After investigating an optimized medium, the major components were found to be molasses and yeast extract, which improved SOD production up to 3.97-fold compared to a synthetic medium. In addition, the optimized medium did not require any induction, which makes it suitable for applications in large-scale production. The SOD formulation was found to increase the stability of the conformational structure and prolong shelf-life. The results show that 1.0% (w/w) trehalose was the best additive, in giving the highest melting temperature by the DSF method and maintaining its activity at more than 80% after storage for 6 months. The obtained SOD was investigated for its cytotoxicity and ROS elimination against fibroblast cells. The results indicate that the SOD enhanced the proliferation and controlled ROS level inside the cells. Thus, the SOD obtained from S. cerevisiae TBRC657 cultured in the optimized medium could be a candidate for use as a ROS scavenger, which can be applied in many industries. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Production of Citric Acid by Aspergillus niger Cultivated in Olive Mill Wastewater Using a Two-Stage Packed Column Bioreactor
Fermentation 2022, 8(4), 153; https://doi.org/10.3390/fermentation8040153 - 30 Mar 2022
Cited by 1 | Viewed by 2694
Abstract
For building a sustainable fermentation process, it is essential to reduce dependence on natural resources and lower the amount of pollution that is created. The reuse of agro-industrial wastewater after possible treatment leads to the achievement of these goals concurrently. This study investigates [...] Read more.
For building a sustainable fermentation process, it is essential to reduce dependence on natural resources and lower the amount of pollution that is created. The reuse of agro-industrial wastewater after possible treatment leads to the achievement of these goals concurrently. This study investigates the production of citric acid and the cellulase enzyme by A. niger cultivated in olive mill wastewater (OMW) using a loofa sponge-packed column bioreactor. The process was conducted under batch conditions using a single-stage packed bioreactor and under continuous operation using two-stage packed-column bioreactors. Citric acid and cellulase enzyme production were enhanced when the culture was supplied with cellulose. Employing loofa sponge slices for cell entrapment/immobilization improved the efficiency of the process. The maximum citric acid concentration achieved was 16 g/L with a yield (YCit.A/BOD) of 38.5% and a productivity of 2.5 g/L/day. When the process parameters were translated into continuous operation employing two loofa sponge-packed column bioreactors, citric acid production was improved significantly to 25 g/L in a steady-state period of 5 days at a production rate of 3.6 g/L/day and an allover yield (YCit.A/BOD) of 57.5%. Cellulases and reducing sugars were continuously supplied to the second-stage bioreactor by the first-stage bioreactor, which in turn enhanced fungal growth and citric acid production. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
N-1 Perfusion Platform Development Using a Capacitance Probe for Biomanufacturing
Bioengineering 2022, 9(4), 128; https://doi.org/10.3390/bioengineering9040128 - 22 Mar 2022
Cited by 2 | Viewed by 1946
Abstract
Fed-batch process intensification with a significantly shorter culture duration or higher titer for monoclonal antibody (mAb) production by Chinese hamster ovary (CHO) cells can be achieved by implementing perfusion operation at the N-1 stage for biomanufacturing. N-1 perfusion seed with much higher final [...] Read more.
Fed-batch process intensification with a significantly shorter culture duration or higher titer for monoclonal antibody (mAb) production by Chinese hamster ovary (CHO) cells can be achieved by implementing perfusion operation at the N-1 stage for biomanufacturing. N-1 perfusion seed with much higher final viable cell density (VCD) than a conventional N-1 batch seed can be used to significantly increase the inoculation VCD for the subsequent fed-batch production (referred as N stage), which results in a shorter cell growth phase, higher peak VCD, or higher titer. In this report, we incorporated a process analytical technology (PAT) tool into our N-1 perfusion platform, using an in-line capacitance probe to automatically adjust the perfusion rate based on real-time VCD measurements. The capacitance measurements correlated linearly with the offline VCD at all cell densities tested (i.e., up to 130 × 106 cells/mL). Online control of the perfusion rate via the cell-specific perfusion rate (CSPR) decreased media usage by approximately 25% when compared with a platform volume-specific perfusion rate approach and did not lead to any detrimental effects on cell growth. This PAT tool was applied to six mAbs, and a platform CSPR of 0.04 nL/cell/day was selected, which enabled rapid growth and maintenance of high viabilities for four of six cell lines. In addition, small-scale capacitance data were used in the scaling-up of N-1 perfusion processes in the pilot plant and in the GMP manufacturing suite. Implementing a platform approach based on capacitance measurements to control perfusion rates led to efficient process development of perfusion N-1 for supporting high-density CHO cell cultures for the fed-batch process intensification. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Enhancement of Labneh Quality by Laser-Induced Modulation of Lactocaseibacillus casei NRRL B-1922
Fermentation 2022, 8(3), 132; https://doi.org/10.3390/fermentation8030132 - 18 Mar 2022
Cited by 2 | Viewed by 1451
Abstract
Labneh is positioned in the top ranking of the bestselling dairy products all over the world due to its health benefits and delicious taste. Labneh production depends mainly on probiotic bacteria in the fermentation of milk. Probiotic bacteria have many health benefits, which [...] Read more.
Labneh is positioned in the top ranking of the bestselling dairy products all over the world due to its health benefits and delicious taste. Labneh production depends mainly on probiotic bacteria in the fermentation of milk. Probiotic bacteria have many health benefits, which are driven by their selective bioactive metabolites that quantitively affect the fermentation products. The current investigation aimed to study the implementation of photobiomodulation through the irradiation of Lacticaseibacillus casei NRRL-B-1922 by a He–Ne laser (630 nm) with different laser doses (3, 6 & 12 J/cm2) prior to milk fermentation. This procedure sought to improve the probiotic bacteria’s activities while enhancing the labneh’s characteristics and consequently produce a more favorable labneh product with better marketing qualities. The photobiostimulated bacterial starter was found to induce increased titratable acidity with the moisture reduction of the labneh product under cold storage conditions for 20 days. The effect was most prominent when using a 12 J/cm2 laser dose. The flavor-aiding components, mainly diacetyl and acetaldehyde compounds, and sensory scores were increased in the labneh produced by irradiated L. casei when compared to the non-radiated probiotic culture after storing the products under cold conditions for 20 consecutive days. Moreover, the antioxidant and proteolytic activities of labneh produced by treated L. casei (12 J/cm2 laser dose) after cold storage were significantly elevated by 41 and 14%, respectively. In conclusion, we can report significantly improved selected characteristics in the final products after the employment of photobiomodulation process, the potential application of this concept on the industrial scale, and its implications on lengthening the product shelf life with improved qualities. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Communication
Continuous Flow Biocatalysis: Synthesis of Coumarin Carboxamide Derivatives by Lipase TL IM from Thermomyces lanuginosus
Catalysts 2022, 12(3), 339; https://doi.org/10.3390/catal12030339 - 17 Mar 2022
Cited by 2 | Viewed by 1236
Abstract
Coumarin carboxamide derivatives are important building blocks for organic synthesis and chemical biology due to their excellent biopharmaceutical properties. In this paper, we demonstrate for the first time a two-step enzymatic synthesis of coumarin carboxamide derivatives. Salicylaldehyde and dimethyl malonate were reacted to [...] Read more.
Coumarin carboxamide derivatives are important building blocks for organic synthesis and chemical biology due to their excellent biopharmaceutical properties. In this paper, we demonstrate for the first time a two-step enzymatic synthesis of coumarin carboxamide derivatives. Salicylaldehyde and dimethyl malonate were reacted to obtain coumarin carboxylate methyl derivatives, which were then reacted with various amines under the catalysis of lipase TL IM from Thermomyces lanuginosus to obtain coumarin carboxamide derivatives in continuous flow reactors. We studied various reaction parameters on the yields. The important features of this method include mild reaction conditions, a short reaction time (40 min), reduced environmental pollution, higher productivity (STY = 31.2941 g L−1 h−1) and enzymes being relatively easy to obtain. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Control System of Liquid Fertilizer Variable-Rate Fertilization Based on Beetle Antennae Search Algorithm
Processes 2022, 10(2), 357; https://doi.org/10.3390/pr10020357 - 12 Feb 2022
Cited by 4 | Viewed by 960
Abstract
In order to solve the problems of low precision of variable-rate fertilization and uneven fertilization flow of field liquid fertilizer applicator, a control system of variable-rate fertilization of liquid fertilizer based on beetle antennae search algorithm was proposed. First of all, this study [...] Read more.
In order to solve the problems of low precision of variable-rate fertilization and uneven fertilization flow of field liquid fertilizer applicator, a control system of variable-rate fertilization of liquid fertilizer based on beetle antennae search algorithm was proposed. First of all, this study established a mathematical model for the variable-rate fertilization control system of liquid fertilizer. Then, according to the control requirements, the search algorithm is used to optimize the three parameters of Proportion Integration Differentiation (PID). Finally, the response time and overshoot of the system are analyzed by software simulation, and the PID control based on beetle antennae search algorithm is compared and analyzed with fuzzy PID control and traditional PID control. The control effect of the control system is verified by a bench test. The results show that the actual response time of the variable-rate fertilization control system based on the beetle antennae search algorithm can reach 2 s, and the average relative error can reach 1.27%. Therefore, the control system of this study can achieve a better control effect, and the control method of this study provides a feasible scheme for the study of variable-rate fertilization. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
An Extended Tissue-like P System Based on Membrane Systems and Quantum-Behaved Particle Swarm Optimization for Image Segmentation
Processes 2022, 10(2), 287; https://doi.org/10.3390/pr10020287 - 31 Jan 2022
Cited by 1 | Viewed by 1077
Abstract
An extended membrane system using a tissue-like P system with evolutional symport/antiport rules and a promoter/inhibitor, which is based on the evolutionary mechanism of quantum-behaved particle swarm optimization (QPSO) and improved QPSO, named CQPSO-ETP, is designed and developed in this paper. The purpose [...] Read more.
An extended membrane system using a tissue-like P system with evolutional symport/antiport rules and a promoter/inhibitor, which is based on the evolutionary mechanism of quantum-behaved particle swarm optimization (QPSO) and improved QPSO, named CQPSO-ETP, is designed and developed in this paper. The purpose of CQPSO-ETP is to enhance the optimization performance of statistical network structure-based membrane-inspired evolutionary algorithms (SNS-based MIEAs) and the QPSO technique. In CQPSO-ETP, evolution rules with a promoter based on a standard QPSO mechanism are introduced to evolve objects, and evolution rules with an inhibitor based on an improved QPSO mechanism using self-adaptive selection, and cooperative evolutionary and logistic chaotic mapping methods, are adopted to avoid prematurity. The communication rules with a promoter/inhibitor for objects are introduced to achieve the exchange and sharing of information between different membranes. Under the control of the evolution and communication mechanism, the CQPSO-ETP can effectively improve the performance with the help of a distributed parallel computing model. The proposed CQPSO-ETP is compared with PSO, QPSO and two existing improved QPSO approaches which are conducted on eight classic numerical benchmark functions to verify the effectiveness. Furthermore, computational experiments which are made on eight tested images with three comparative clustering approaches are adopted, and the experimental results demonstrate the clustering validity of the proposed CQPSO-ETP. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Optimization of 2-Phenylethanol Production from Sweet Whey Fermentation Using Kluyveromyces marxianus
Fermentation 2022, 8(2), 39; https://doi.org/10.3390/fermentation8020039 - 19 Jan 2022
Cited by 3 | Viewed by 1595
Abstract
The growing demand for natural products benefits the development of bioprocesses to obtain value-added compounds using residues such as sweet whey, which is rich in lactose. The yeast Kluyveromyces marxianus can ferment sweet whey to obtain 2-phenylethanol (2-PhEtOH), which is a superior alcohol [...] Read more.
The growing demand for natural products benefits the development of bioprocesses to obtain value-added compounds using residues such as sweet whey, which is rich in lactose. The yeast Kluyveromyces marxianus can ferment sweet whey to obtain 2-phenylethanol (2-PhEtOH), which is a superior alcohol with a rose aroma. Such fermentation only requires the addition of L-phenylalanine (precursor) and (NH4)2SO4 (salt). Therefore, it was sought to improve the fermentation conditions to produce 2-PhEtOH, which, in turn, would achieve the maximum decrease in the Chemical Oxygen Demand (COD) of the fermentation medium. With the use of the Response Surface Methodology and the application of a Central Composite Design for optimization, two parameters were evaluated as a function of time: salt concentration and precursor. The experimental data were adjusted to a second order polynomial, identifying that the precursor concentration presents a statistically significant effect. The best conditions were: 4.50 g/L of precursor and 0.76 g/L of salt, with a maximum production of 1.2 g/L (2-PhEtOH) at 48 h and achieving a maximum percentage of COD removal of 76% at 96 h. Finally, the optimal conditions were experimentally validated, recommending the use of the model. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Enhanced Beetle Antennae Algorithm for Chemical Dynamic Optimization Problems’ Non-Fixed Points Discrete Solution
by , , and
Processes 2022, 10(1), 148; https://doi.org/10.3390/pr10010148 - 11 Jan 2022
Cited by 4 | Viewed by 760
Abstract
Dynamic optimization is an important research topic in chemical process control. A dynamic optimization method with good performance can reduce energy consumption and prompt production efficiency. However, the method of solving the problem is complicated in the establishment of the model, and the [...] Read more.
Dynamic optimization is an important research topic in chemical process control. A dynamic optimization method with good performance can reduce energy consumption and prompt production efficiency. However, the method of solving the problem is complicated in the establishment of the model, and the process of solving the optimal value has a certain degree of difficulty. Based on this, we proposed a non-fixed points discrete method of an enhanced beetle antennae optimization algorithm (EBSO) to solve this kind of problem. Firstly, we converted individual beetles into groups of beetles to search for the best and increase the diversity of the population. Secondly, we introduced a balanced direction strategy, which explored extreme values in new directions before the beetles updated their positions. Finally, a spiral flight mechanism was introduced to change the situation of the beetles flying straight toward the tentacles to prevent the traditional algorithm from easily falling into a certain local range and not being able to jump out. We applied the enhanced algorithm to four classic chemical problems. Meanwhile, we changed the equal time division method or unequal time division method commonly used to solve chemical dynamic optimization problems, and proposed a new interval distribution method—the non-fixed points discrete method, which can more accurately represent the optimal control trajectory. The comparison and analysis of the simulation test results with other algorithms for solving chemical dynamic optimization problems show that the EBSO algorithm has good performance to a certain extent, which further proves the effectiveness of the EBSO algorithm and has a better optimization ability. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Approximate Models of Microbiological Processes in a Biofilm Formed on Fine Spherical Particles
Processes 2022, 10(1), 48; https://doi.org/10.3390/pr10010048 - 27 Dec 2021
Viewed by 1250
Abstract
This paper concerns the dynamical modeling of the microbiological processes that occur in the biofilms that are formed on fine inert particles. Such biofilm forms e.g. in fluidized-bed bio-reactors, expanded bed biofilm reactors and biofilm air-lift suspension reactors. An approximate model that is [...] Read more.
This paper concerns the dynamical modeling of the microbiological processes that occur in the biofilms that are formed on fine inert particles. Such biofilm forms e.g. in fluidized-bed bio-reactors, expanded bed biofilm reactors and biofilm air-lift suspension reactors. An approximate model that is based on the Laplace–Carson transform and a family of approximate models that are based on the concept of the pseudo-stationary substrate concentration profile in the biofilm were proposed. The applicability of the models to the microbiological processes was evaluated following Monod or Haldane kinetics in the conditions of dynamical biofilm growth. The use of approximate models significantly simplifies the computations compared to the exact one. Moreover, the stiffness that was present in the exact model, which was solved numerically by the method of lines, was eliminated. Good accuracy was obtained even for large internal mass transfer resistances in the biofilm. It was shown that significantly higher accuracy was obtained using one of the proposed models than that which was obtained using the previously published approximate model that was derived using the homotopy analysis method. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Optimization of Soybean Meal Fermentation for Aqua-Feed with Bacillus subtilis natto Using the Response Surface Methodology
Fermentation 2021, 7(4), 306; https://doi.org/10.3390/fermentation7040306 - 10 Dec 2021
Cited by 7 | Viewed by 2615
Abstract
This study aimed to improve the nutritional value of soybean meal (SBM) by solid-state fermentation (SSF) using Bacillus subtilis natto (B. s. natto) to overcome the limitations of SBM usage in aquafeed. The response surface methodology (RSM) was employed to explore [...] Read more.
This study aimed to improve the nutritional value of soybean meal (SBM) by solid-state fermentation (SSF) using Bacillus subtilis natto (B. s. natto) to overcome the limitations of SBM usage in aquafeed. The response surface methodology (RSM) was employed to explore the relationships of fermentation conditions, such as temperature, time, water-substrate ratio, and layer thickness, on the degree of protein hydrolysis (DH) and the crude protein (CP) content. The optimum conditions for achieving the higher DH (15.96%) and CP (55.76%) were 43.82 °C, 62.32 h, 1.08 of water-substrate ratio, and a layer thickness of 2.02 cm. CP and DH in the fermented soybean meal (FSM) increased by 9.8% and 177.1%, respectively, and crude fiber decreased by 14.1% compared to SBM. The protein dispersibility index (PDI) decreased by 29.8%, while KOH protein solubility (KPS) was significantly increased by 17.4%. Flavonoids and total phenolic acid content in FSM were increased by 231.0% and 309.4%, respectively. Neutral protease activity (NPA) also reached a high level (1723.6 U g−1). Total essential amino acids (EAA) in FSM increased by 12.2%, higher than the 10.8% increase of total non-essential amino acids (NEAA), while the total free amino acids content was 12.76 times higher than that of SBM. Major anti-nutritional factors in SBM were significantly reduced during the process, and almost all SBM protein macromolecules were decomposed. Together with the cost-effectiveness of SSF, B. s. natto-fermented SBM products have great potential to improve the plant composition and replace high-cost ingredients in aquafeed, contributing to food security and environmental sustainability. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Tryptophan Production Maximization in a Fed-Batch Bioreactor with Modified E. coli Cells, by Optimizing Its Operating Policy Based on an Extended Structured Cell Kinetic Model
Bioengineering 2021, 8(12), 210; https://doi.org/10.3390/bioengineering8120210 - 10 Dec 2021
Cited by 3 | Viewed by 1597
Abstract
Hybrid kinetic models, linking structured cell metabolic processes to the dynamics of macroscopic variables of the bioreactor, are more and more used in engineering evaluations to derive more precise predictions of the process dynamics under variable operating conditions. Depending on the cell model [...] Read more.
Hybrid kinetic models, linking structured cell metabolic processes to the dynamics of macroscopic variables of the bioreactor, are more and more used in engineering evaluations to derive more precise predictions of the process dynamics under variable operating conditions. Depending on the cell model complexity, such a math tool can be used to evaluate the metabolic fluxes in relation to the bioreactor operating conditions, thus suggesting ways to genetically modify the microorganism for certain purposes. Even if development of such an extended dynamic model requires more experimental and computational efforts, its use is advantageous. The approached probative example refers to a model simulating the dynamics of nanoscale variables from several pathways of the central carbon metabolism (CCM) of Escherichia coli cells, linked to the macroscopic state variables of a fed-batch bioreactor (FBR) used for the tryptophan (TRP) production. The used E. coli strain was modified to replace the PTS system for glucose (GLC) uptake with a more efficient one. The study presents multiple elements of novelty: (i) the experimentally validated modular model itself, and (ii) its efficiency in computationally deriving an optimal operation policy of the FBR. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Effectively Synthesizing SO4/TiO2 Catalyst and Its Performance for Converting Ethanol into Diethyl Ether (DEE)
Catalysts 2021, 11(12), 1492; https://doi.org/10.3390/catal11121492 - 06 Dec 2021
Cited by 4 | Viewed by 1685
Abstract
This SO4/TiO2 catalyst as a heterogeneous acidic catalyst was synthesized in various concentrations of H2SO4. The activity and selectivity of the SO4/TiO2 catalyst on the dehydration reaction of ethanol to diethyl ether were [...] Read more.
This SO4/TiO2 catalyst as a heterogeneous acidic catalyst was synthesized in various concentrations of H2SO4. The activity and selectivity of the SO4/TiO2 catalyst on the dehydration reaction of ethanol to diethyl ether were studied as well. The SO4/TiO2 was prepared from TiO2 powder by wet impregnation method with a various aqueous solution of H2SO4 (1; 2; 3 M H2SO4) and calcination temperature (400, 500, and 600 °C) to obtain a catalyst with optimum acidity. The catalysts were characterized using FTIR, XRD, SEM-EDX, SAA, TGA/DSC, and acidity test gravimetrically with ammonia. The liquid product of DEE was analyzed by gas chromatography (GC) to analyze the selectivity of the catalyst. The catalyst TS-3-400 had the highest activity and selectivity in the dehydration reaction of ethanol to diethyl ether at a temperature of 225 °C, with a conversion of 51.83% and a DEE selectivity of 1.72%. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Mechanisms Driving Microbial Community Composition in Anaerobic Co-Digestion of Waste-Activated Sewage Sludge
Bioengineering 2021, 8(12), 197; https://doi.org/10.3390/bioengineering8120197 - 30 Nov 2021
Cited by 3 | Viewed by 1794
Abstract
Anaerobic co-digestion (Co-AD) is used to increase the effectiveness of anaerobic digestion (AD) using local “wastes”, adding economic and environmental benefits. Since system stability is of existential importance for the operation of wastewater treatment plants, thorough testing of potential co-substrates and their effects [...] Read more.
Anaerobic co-digestion (Co-AD) is used to increase the effectiveness of anaerobic digestion (AD) using local “wastes”, adding economic and environmental benefits. Since system stability is of existential importance for the operation of wastewater treatment plants, thorough testing of potential co-substrates and their effects on the respective community and system performance is crucial for understanding and utilizing Co-AD to its best capacity. Food waste (FW) and canola lecithin (CL) were tested in mesophilic, lab-scale, semi-continuous reactors over a duration of 120 days with stepwise increased substrate addition. Key performance indicators (biogas, total/volatile solids, fatty acids) were monitored and combined with 16S-rRNA amplicon sequencing to assess the impact of co-substrate addition on reactor performance and microbial community composition (MCC). Additionally, the latter was then compared with natural shifts occurring in the wastewater treatment plant (WWTP, source) at the same time. An almost linear increase in biogas production with both co-substrates at an approximate 1:1 ratio with the organic loading rate (OLR) was observed. The MCCs in both experiments were mostly stable, but also prone to drift over time. The FW experiment MCC more closely resembled the original WWTP community and the observed shifts indicated high levels of functional redundancy. Exclusive to the CL co-substrate, a clear selection for a few operational taxonomic units (OTUs) was observed. There was little evidence for a persistent invasion and establishment of microorganisms from typical primary substrates into the stable resident community of the reactors, which is in line with earlier findings that suggested that the inoculum and history mostly define the MCC. However, external factors may still tip the scales in favor of a few r-strategists (e.g., Prolixibacter) in an environment that otherwise favors K-strategists, which may in fact also be recruited from the primary substrate (Trichococcus). In our study, specialization and diversity loss were also observed in response to the addition of the highly specialized CL, which in turn, may have adverse effects on the system’s stability and reduced resilience and recovery. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Mathematical Model for Scaling up Bioprocesses Using Experiment Design Combined with Buckingham Pi Theorem
Appl. Sci. 2021, 11(23), 11338; https://doi.org/10.3390/app112311338 - 30 Nov 2021
Cited by 5 | Viewed by 1104
Abstract
Scaling up bioprocesses from the experimental to the pilot or industrial scale involves heuristics and scale relationships that are far from the specific phenomena and are usually not connected to the experimental data. In complex systems, the scaling-up methodology must connect the experimental [...] Read more.
Scaling up bioprocesses from the experimental to the pilot or industrial scale involves heuristics and scale relationships that are far from the specific phenomena and are usually not connected to the experimental data. In complex systems, the scaling-up methodology must connect the experimental data with the tools of engineering design. In this work, a two-stage gold bioleaching process was used as a case study to develop a mathematical model of bioprocess scaling that combines the design of experiments with dimensional analysis using the Buckingham Pi theorem to formulate a predictive model that allows scaling up bioprocesses. It was found that the C/N, C/K, and T/C ratios are dimensionless factors that can explain the behavior of a system. Using the Pearson Product–Moment bivariate analysis, it was found that the dimensionless factors C/N and C/K were correlated with the leaching potential of the fermented broth at 1060 cm−1. With these results, a non-linear logarithmic model based on dimensionless parameters was proposed to explain the behavior of the system with a correlation coefficient of R2 = 0.9889, showing that the optimal conditions to produce fermented broth comprised a C/N ratio close to 50 and a C/K ratio close to 800, which allows predicting the scaling of the bioprocess. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Bioreactor Rhamnolipid Production Using Palm Oil Agricultural Refinery By-Products
Processes 2021, 9(11), 2037; https://doi.org/10.3390/pr9112037 - 14 Nov 2021
Cited by 2 | Viewed by 1315
Abstract
Palm fatty acid distillate (PFAD) and fatty acid methyl ester (FAME) are used by P. aeruginosa PAO1 to produce rhamnolipid biosurfactant. The process of fermentation producing of biosurfactant was structured in a 2 L bioreactor using 2% of PFAD and FAME as carbon [...] Read more.
Palm fatty acid distillate (PFAD) and fatty acid methyl ester (FAME) are used by P. aeruginosa PAO1 to produce rhamnolipid biosurfactant. The process of fermentation producing of biosurfactant was structured in a 2 L bioreactor using 2% of PFAD and FAME as carbon sources in minimal medium and with a nitrogen concentration of 1 g L−1. Mass spectrometry results show the crude biosurfactant produced was predominantly monorhamnolipid (Rha-C10-C10) and dirhamnolipid (Rha-Rha-C10-C10) at 503 and 649 m/z value for both substrates. Maximum production of crude rhamnolipid for PFAD was 1.06 g L−1 whereas for FAME it was 2.1 g L−1, with a reduction in surface tension of Tris-HCl pH 8.0 solution to 28 mN m−1 and a critical micelle concentration (CMC) of 26 mg L−1 measured for both products. Furthermore, the 24 h emulsification indexes in kerosene, hexadecane, sunflower oil, and rapeseed oil using 1 g L−1 of crude rhamnolipid were in the range 20–50%. Consequently, PFAD and FAME, by-products from the agricultural refining of palm oil, may result in a product that has a higher added-value, rhamnolipid biosurfactant, in the process of integrated biorefinery. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
A Design of a Solar Fermentation System on Chicken Manure by Fuzzy Logic Temperature Control
Appl. Sci. 2021, 11(22), 10703; https://doi.org/10.3390/app112210703 - 12 Nov 2021
Viewed by 809
Abstract
Traditional chicken manure fermentation is mostly natural composting or exposure, which is not only time consuming but also susceptible to weather, resulting in uncontrollable quality and environmental pollution. This research aims to build a smart solar chicken manure fermentation system to control the [...] Read more.
Traditional chicken manure fermentation is mostly natural composting or exposure, which is not only time consuming but also susceptible to weather, resulting in uncontrollable quality and environmental pollution. This research aims to build a smart solar chicken manure fermentation system to control the conditions of chicken manure fermentation effectively, improve quality, and solve the problems of environmental pollution. Hot water produced by solar energy is the heat source for the main system of fermentation, and a backup supplemental heat source by gas heater is applied. The mechanism of drive, agitation, ventilation and drying as well as temperature conditions are controlled by the Arduino’s control core. Fuzzy logic is applied to maintain the optimal temperature, so that the system decomposes the bacteria optimally and reduces the consumed time for fermentation. The chicken manure humidity can be decreased from 70% to 30%, and the effective control system temperature is between 40 and 42 °C, while the pH value is changed from 8.7 to 7.4. The sample analysis of the fermentation also shows that there was 13.12% more organic matter in the chicken manure that added the decomposing bacteria than which did not contain the decomposing bacteria. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Impact of Operational Factors, Inoculum Origin, and Feedstock Preservation on the Biochemical Methane Potential
Bioengineering 2021, 8(11), 176; https://doi.org/10.3390/bioengineering8110176 - 05 Nov 2021
Cited by 2 | Viewed by 915
Abstract
Anaerobic digestion for the valorization of organic wastes into biogas is gaining worldwide interest. Nonetheless, the sizing of the biogas plant units require knowledge of the quantity of feedstock, and their associated methane potentials, estimated widely by Biochemical Methane Potential (BMP) tests. Discrepancies [...] Read more.
Anaerobic digestion for the valorization of organic wastes into biogas is gaining worldwide interest. Nonetheless, the sizing of the biogas plant units require knowledge of the quantity of feedstock, and their associated methane potentials, estimated widely by Biochemical Methane Potential (BMP) tests. Discrepancies exist among laboratories due to variability of protocols adopted and operational factors used. The aim of this study is to verify the influence of some operational factors (e.g., analysis frequency, trace elements and vitamins solution addition and flushing gas), feedstock conservation and the source of inoculum on BMP. Among the operational parameters tested on cellulose degradation, only the type of gas used for flushing headspace of BMP assays had shown a significant influence on methane yields from cellulose. Methane yields of 344 ± 6 NL CH4 kg−1 VS and 321 ± 10 NL CH4 kg−1 VS obtained from assays flushed with pure N2 and N2/CO2 (60/40 v/v). The origin of inoculum (fed in co-digestion) only significantly affected the methane yields for straw, 253 ± 3 and 333 ± 3 NL CH4 kg−1 VS. Finally, freezing/thawing cycle effect depended of the substrate (tested on biowaste, manure, straw and WWTP sludge) with a possible effect of water content substrate. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Multi-Time and Multi-Band CSP Motor Imagery EEG Feature Classification Algorithm
Appl. Sci. 2021, 11(21), 10294; https://doi.org/10.3390/app112110294 - 02 Nov 2021
Cited by 2 | Viewed by 1211
Abstract
The effective decoding of motor imagination EEG signals depends on significant temporal, spatial, and frequency features. For example, the motor imagination of the single limbs is embodied in the μ (8–13 Hz) rhythm and β (13–30 Hz) rhythm in frequency features. However, the [...] Read more.
The effective decoding of motor imagination EEG signals depends on significant temporal, spatial, and frequency features. For example, the motor imagination of the single limbs is embodied in the μ (8–13 Hz) rhythm and β (13–30 Hz) rhythm in frequency features. However, the significant temporal features are not necessarily manifested in the whole motor imagination process. This paper proposes a Multi-Time and Frequency band Common Space Pattern (MTF-CSP)-based feature extraction and EEG decoding method. The MTF-CSP learns effective motor imagination features from a weak Electroencephalogram (EEG), extracts the most effective time and frequency features, and identifies the motor imagination patterns. Specifically, multiple sliding window signals are cropped from the original signals. The multi-frequency band Common Space Pattern (CSP) features extracted from each sliding window signal are fed into multiple Support Vector Machine (SVM) classifiers with the same parameters. The Effective Duration (ED) algorithm and the Average Score (AS) algorithm are proposed to identify the recognition results of multiple time windows. The proposed method is trained and evaluated on the EEG data of nine subjects in the 2008 BCI-2a competition dataset, including a train dataset and a test dataset collected in other sessions. As a result, the average cross-session recognition accuracy of 78.7% was obtained on nine subjects, with a sliding window length of 1 s, a step length of 0.4 s, and the six windows. Experimental results showed the proposed MTF-CSP outperforming the compared machine learning and CSP-based methods using the original signals or other features such as time-frequency picture features in terms of accuracy. Further, it is shown that the performance of the AS algorithm is significantly better than that of the Max Voting algorithm adopted in other studies. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Design and Stiffness Optimization of Bionic Docking Mechanism for Space Target Acquisition
Appl. Sci. 2021, 11(21), 10278; https://doi.org/10.3390/app112110278 - 02 Nov 2021
Cited by 4 | Viewed by 798
Abstract
Aiming at the soft contact problem of space docking, a bionic docking mechanism for space target acquisition is proposed to realize the buffering and unloading of six–dimensional spatial collision through flexible rotating and linear components. Using the Kane method, an integrated dynamic equation [...] Read more.
Aiming at the soft contact problem of space docking, a bionic docking mechanism for space target acquisition is proposed to realize the buffering and unloading of six–dimensional spatial collision through flexible rotating and linear components. Using the Kane method, an integrated dynamic equation of the bionic docking mechanism in space docking is established, and the stiffness optimization strategy is carried out based on angular momentum conservation. Based on the particle swarm optimization (PSO), a stiffness optimization scheme was realized. Through the numerical simulation of the bionic docking mechanism in space docking, the stiffness optimization was achieved and the soft contact machine process is verified. Finally, through the docking collision experiments in Adams, the results indicate that the proposed bionic docking mechanism can not only prolong the collision time to win time for space acquisition, but also buffer and unload the six–dimensional spatial collision caused by space target docking. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Monte Carlo-Based Error Propagation for a More Reliable Regression Analysis across Specific Rates in Bioprocesses
Bioengineering 2021, 8(11), 160; https://doi.org/10.3390/bioengineering8110160 - 26 Oct 2021
Cited by 1 | Viewed by 1376
Abstract
During process development, bioprocess data need to be converted into applicable knowledge. Therefore, it is crucial to evaluate the obtained data under the usage of transparent and reliable data reduction and correlation techniques. Within this contribution, we show a generic Monte Carlo error [...] Read more.
During process development, bioprocess data need to be converted into applicable knowledge. Therefore, it is crucial to evaluate the obtained data under the usage of transparent and reliable data reduction and correlation techniques. Within this contribution, we show a generic Monte Carlo error propagation and regression approach applied to two different, industrially relevant cultivation processes. Based on measurement uncertainties, errors for cell-specific growth, uptake, and production rates were determined across an evaluation chain, with interlinked inputs and outputs. These uncertainties were subsequently included in regression analysis to derive the covariance of the regression coefficients and the confidence bounds for prediction. The usefulness of the approach is shown within two case studies, based on the relations across biomass-specific rate control limits to guarantee high productivities in E. coli, and low lactate formation in a CHO cell fed-batch could be established. Besides the possibility to determine realistic errors on the evaluated process data, the presented approach helps to differentiate between reliable and unreliable correlations and prevents the wrong interpretations of relations based on uncertain data. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Evaluation of Non-Encapsulated and Microencapsulated Lactic Acid Bacteria
Appl. Sci. 2021, 11(21), 9867; https://doi.org/10.3390/app11219867 - 22 Oct 2021
Cited by 3 | Viewed by 1248
Abstract
A total of 15 strains of lactic acid bacteria (LAB) were isolated from the broiler chicken’s gastrointestinal tract. All isolates were phenotypical and genetically identified. Among these isolates, only six were biochemical (API 50 CHL and ABIS soft) and genetically (16S rRNA sequencing) [...] Read more.
A total of 15 strains of lactic acid bacteria (LAB) were isolated from the broiler chicken’s gastrointestinal tract. All isolates were phenotypical and genetically identified. Among these isolates, only six were biochemical (API 50 CHL and ABIS soft) and genetically (16S rRNA sequencing) confirmed as Lactobacillus acidophilus, Limosilactobacillus fermentum, Levilactobacillus brevis, and Ligilactobacillus salivarius. Probiotic properties, including tolerance to pH (pH 2.0 and 3.0), bile salts (0.3% oxgall), hemolysis activity, and antibiotic susceptibility, were evaluated. Three isolates of the latter isolates showed high resistance at low pH values (73.74% to 98.20%) and bile salt concentrations (77.89% to 99.49%). The antibiotic test presented 100% resistance of LAB to gentamicin, lincomycin, enrofloxacin, and streptomycin lower than the 0.5 mm inhibition zone diameter. Selected strains (L. acidophilus IBNA 64, L. salivarius IBNA 33, and L. salivarius IBNA 41) were exposed to the spray-drying process based on observable probiotic potential. A maltodextrin-glucose solution was used as a thermoprotectant. After spray drying, a reduction in strain viability was noted (108 to 104 CFU/g). In conclusion, only L. salivarius (IBNA 33 and IBNA 41) could be used as a possible probiotic, and further studies are needed to ensure their safe application in the animal nutrition field with beneficial effects for improving performance and pathogen microorganism control from intestines equilibrating the microbiota composition. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Metabolic Reaction Network-Based Model Predictive Control of Bioprocesses
Appl. Sci. 2021, 11(20), 9532; https://doi.org/10.3390/app11209532 - 14 Oct 2021
Cited by 1 | Viewed by 912
Abstract
Bioprocesses are increasingly used for the production of high added value products. Microorganisms are used in bioprocesses to mediate or catalyze the necessary reactions. This makes bioprocesses highly nonlinear and the governing mechanisms are complex. These complex governing mechanisms can be modeled by [...] Read more.
Bioprocesses are increasingly used for the production of high added value products. Microorganisms are used in bioprocesses to mediate or catalyze the necessary reactions. This makes bioprocesses highly nonlinear and the governing mechanisms are complex. These complex governing mechanisms can be modeled by a metabolic network that comprises all interactions within the cells of the microbial population present in the bioprocess. The current state of the art in bioprocess control is model predictive control based on the use of macroscopic models, solely accounting for substrate, biomass, and product mass balances. These macroscopic models do not account for the underlying mechanisms governing the observed process behavior. Consequently, opportunities are missed to fully exploit the available process knowledge to operate the process in a more sustainable manner. In this article, a procedure is presented for metabolic network-based model predictive control. This procedure uses a combined moving horizon-model predictive control strategy to monitor the flux state and optimize the bioprocess under study. A CSTR bioreactor model has been combined with a small-scale metabolic network to illustrate the performance of the presented procedure. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Variable Neighborhood Strategy Adaptive Search for Optimal Parameters of SSM-ADC 12 Aluminum Friction Stir Welding
Processes 2021, 9(10), 1805; https://doi.org/10.3390/pr9101805 - 11 Oct 2021
Cited by 2 | Viewed by 1161
Abstract
In this study, we present a new algorithm for finding the optimal friction stir welding parameters to maximize the tensile strength of a butt joint made of the semisolid material (SSM) ADC 12 aluminum. The welding parameters were rotational speed, welding speed, tool [...] Read more.
In this study, we present a new algorithm for finding the optimal friction stir welding parameters to maximize the tensile strength of a butt joint made of the semisolid material (SSM) ADC 12 aluminum. The welding parameters were rotational speed, welding speed, tool tilt, tool pin profile, and rotational direction. The method presented is a variable neighborhood strategy adaptive search (VaNSAS) approach. The process of finding the optimal friction stir welding parameters comprises five steps: (1) identifying the type and range of friction stir parameters using a literature survey; (2) performing experiments according to (1); (3) constructing a regression model using the response surface method optimizer (RSM optimizer); (4) using VaNSAS to find the optimal parameters for the model obtained from (3); and (5) confirming the results from (4) using the parameter levels obtained from (4) to perform real experiments. The computational results revealed that the tensile strength generated from VaNSAS was 3.67% higher than the tensile strength obtained from the RSM optimizer parameters. The optimal parameters obtained from VaNSAS were a rotation speed of 2200 rpm, a welding speed of 108.34 mm/min, a tool tilt of 1.23 Deg, a tool pin profile of a hexagon, and a rotational direction of clockwise. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
Effect of Pyrolysis Conditions on the Performance of Co–Doped MOF–Derived Carbon Catalysts for Oxygen Reduction Reaction
Catalysts 2021, 11(10), 1163; https://doi.org/10.3390/catal11101163 - 27 Sep 2021
Cited by 3 | Viewed by 1624
Abstract
MOF–derived porous carbon is a type of promising catalyst to replace expensive Pt–based catalysts for oxygen reduction reaction (ORR). The catalytic activity for ORR depends closely on pyrolysis conditions. In this work, a Co–doped ZIF–8 material was chosen as a research object. The [...] Read more.
MOF–derived porous carbon is a type of promising catalyst to replace expensive Pt–based catalysts for oxygen reduction reaction (ORR). The catalytic activity for ORR depends closely on pyrolysis conditions. In this work, a Co–doped ZIF–8 material was chosen as a research object. The effect of pyrolysis conditions (temperature, heating rate, two–step heating) on the ORR performance of ZIF–derived carbon catalysts was systematically studied. The Co–ZIF–8 catalyst carbonized at 900 °C exhibits better ORR catalytic activity than that carbonized at 800 °C and 1000 °C. Moreover, a low heating rate can enhance catalytic activity. Two–step pyrolysis is proven to be an effective way to improve the performance of catalysts. Reducing the heating rate in the low–temperature stage is more beneficial to the ORR performance, compared to the heating rate in the high–temperature stage. The results show that the Co–ZIF–8 catalyst exhibits the best performance when the precursor was heated to 350 °C at 2 °C/min, and then heated to 900 °C at 5 °C/min. The optimum Co–ZIF–8 catalyst shows a half–wave potential of 0.82 V and a current density of 5.2 mA·cm−2 in 0.1 M KOH solution. It also exhibits high content of defects and good graphitization. TEM mapping shows that Co and N atoms are highly dispersed in the polyhedral carbon skeleton. However, two–step pyrolysis has no significant effect on the stability of the catalyst. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
A Multi–Membrane System to Study the Effects of Physical and Metabolic Interactions in Microbial Co-Cultures and Consortia
Fermentation 2021, 7(4), 206; https://doi.org/10.3390/fermentation7040206 - 24 Sep 2021
Viewed by 1480
Abstract
Continuous cell-to-cell contact between different species is a general feature of all natural environments. However, almost all research is conducted on single-species cultures, reflecting a biotechnological bias and problems associated with the complexities of reproducibly growing and controlling multispecies systems. Consequently, biotic stress [...] Read more.
Continuous cell-to-cell contact between different species is a general feature of all natural environments. However, almost all research is conducted on single-species cultures, reflecting a biotechnological bias and problems associated with the complexities of reproducibly growing and controlling multispecies systems. Consequently, biotic stress due to the presence of other species remains poorly understood. In this context, understanding the effects of physical contact between species when compared to metabolic contact alone is one of the first steps to unravelling the mechanisms that underpin microbial ecological interactions. The current technologies to study the effects of cell-to-cell contact present disadvantages, such as the inefficient or discontinuous exchange of metabolites when preventing contact between species. This paper presents and characterizes a novel bioreactor system that uses ceramic membranes to create a “multi-membrane” compartmentalized system whereby two or more species can be co-cultured without the mixing of the species, while ensuring the efficient sharing of all of the media components. The system operates continuously, thereby avoiding the discontinuities that characterize other systems, which either have to use hourly backwashes to clean their membranes, or have to change the direction of the flow between compartments. This study evaluates the movement of metabolites across the membrane in co-cultures of yeast, microalgae and bacterial species, and monitors the movement of the metabolites produced during co-culturing. These results show that the multi-membrane system proposed in this study represents an effective system for studying the effects of cell-to-cell contact in microbial consortia. The system can also be adapted for various biotechnological purposes, such as the production of metabolites when more than one species is required for such a process. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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Article
The Effect of the Expression of the Antiapoptotic BHRF1 Gene on the Metabolic Behavior of a Hybridoma Cell Line
Appl. Sci. 2021, 11(14), 6258; https://doi.org/10.3390/app11146258 - 06 Jul 2021
Viewed by 1347
Abstract
One of the most important limitations of mammalian cells-based bioprocesses, and particularly hybridoma cell lines, is the accelerated metabolism related to glucose and glutamine consumption. The high uptake rates of glucose and glutamine (i.e., the main sources of carbon, nitrogen and energy) lead [...] Read more.
One of the most important limitations of mammalian cells-based bioprocesses, and particularly hybridoma cell lines, is the accelerated metabolism related to glucose and glutamine consumption. The high uptake rates of glucose and glutamine (i.e., the main sources of carbon, nitrogen and energy) lead to the production and accumulation of large amounts of lactate and ammonia in culture broth. Lactate and/or ammonia accumulation, together with the depletion of the main nutrients, are the major causes of apoptosis in hybridoma cell cultures. The KB26.5 hybridoma cell line, producing an IgG3, was engineered with BHRF1 (KB26.5-BHRF1), an Epstein–Barr virus-encoded early protein homologous to the antiapoptotic protein Bcl-2, with the aim of protecting the hybridoma cell line from apoptosis. Surprisingly, besides achieving effective protection from apoptosis, the expression of BHRF1 modified the metabolism of the hybridoma cell line. Cell physiology and metabolism analyses of the original KB26.5 and KB26.5-BHRF1 revealed an increase of cell growth rate, a reduction of glucose and glutamine consumption, as well as a decrease in lactate secretion in KB26.5-BHRF1 cells. A flux balance analysis allowed us to quantify the intracellular fluxes of both cell lines. The main metabolic differences were identified in glucose consumption and, consequently, the production of lactate. The lactate production flux was reduced by 60%, since the need for NADH regeneration in the cytoplasm decreased due to a more than 50% reduction in glucose uptake. In general terms, the BHRF1 engineered cell line showed a more efficient metabolism, with an increase in biomass volumetric productivity under identical culture conditions. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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