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18 pages, 12396 KiB

Open AccessArticle

Fungal Lignocellulose Utilisation Strategies from a Bioenergetic Perspective: Quantification of Related Functional Traits Using Biocalorimetry

by Hieu Linh Duong, Sven Paufler, Hauke Harms, Dietmar Schlosser and Thomas Maskow

Microorganisms 2022, 10(8), 1675; https://doi.org/10.3390/microorganisms10081675 - 19 Aug 2022

Cited by 3 | Viewed by 2393

Abstract

In the present study, we investigated whether a non-invasive metabolic heat flux analysis could serve the determination of the functional traits in free-living saprotrophic decomposer fungi and aid the prediction of fungal influences on ecosystem processes. For this, seven fungi, including ascomycete, basidiomycete, and zygomycete species, were investigated in a standardised laboratory environment, employing wheat straw as a globally relevant lignocellulosic substrate. Our study demonstrates that biocalorimetry can be employed successfully to determine growth-related fungal activity parameters, such as apparent maximum growth rates (AMGR), cultivation times until the observable onset of fungal growth at AMGR (t_AMGR), quotients formed from the AMGR and t_AMGR (herein referred to as competitive growth potential, CGP), and heat yield coefficients (Y_Q/X), the latter indicating the degree of resource investment into fungal biomass versus other functional attributes. These parameters seem suitable to link fungal potentials for biomass production to corresponding ecological strategies employed during resource utilisation, and therefore may be considered as fungal life history traits. A close connection exists between the CGP and Y_Q/X values, which suggests an interpretation that relates to fungal life history strategies. Full article

(This article belongs to the Special Issue Advances in Monitoring Metabolic Activities of Microorganisms by Calorimetry)

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14 pages, 3231 KiB

Open AccessFeature PaperArticle

Novel Strategy for the Calorimetry-Based Control of Fed-Batch Cultivations of Saccharomyces cerevisiae

by Jérémy Kottelat, Brian Freeland and Michal Dabros

Processes 2021, 9(4), 723; https://doi.org/10.3390/pr9040723 - 20 Apr 2021

Cited by 7 | Viewed by 3867

Abstract

Typical controllers for fed-batch cultivations are based on the estimation and control of the specific growth rate in real time. Biocalorimetry allows one to measure a heat signal proportional to the substrate consumed by cells. The derivative of this heat signal is usually used to evaluate the specific growth rate, introducing noise to the resulting estimate. To avoid this, this study investigated a novel controller based directly on the heat signal. Time trajectories of the heat signal setpoint were modelled for different specific growth rates, and the controller was set to follow this dynamic setpoint. The developed controller successfully followed the setpoint during aerobic cultivations of Saccharomyces cerevisiae, preventing the Crabtree effect by maintaining low glucose concentrations. With this new method, fed-batch cultivations of S. cerevisiae could be reliably controlled at specific growth rates between 0.075 h⁻¹ and 0.20 h⁻¹_, with average root mean square errors of 15 ± 3%. Full article

(This article belongs to the Special Issue Bioreactor System: Design, Modeling and Continuous Production Process)

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22 pages, 1927 KiB

Open AccessArticle

The Application of Dielectric Spectroscopy and Biocalorimetry for the Monitoring of Biomass in Immobilized Mammalian Cell Cultures

by Harriet E. Cole, Aurélie Demont and Ian W. Marison

Processes 2015, 3(2), 384-405; https://doi.org/10.3390/pr3020384 - 7 May 2015

Cited by 17 | Viewed by 10177

Abstract

The purpose of this study was to introduce dielectric spectroscopy and biocalorimetry as monitoring methods to follow immobilised Chinese Hamster Ovary (CHO) cell culture development. The theory behind both monitoring techniques is explained and perfusion cultures are performed in a Reaction Calorimeter (eRC1 from Mettler Toledo) as an application example. The findings of this work show that dielectric spectroscopy gives highly reliable information upon the viable cell density throughout the entire culture. On the other hand, the RC1 could only provide accurate data from day 5, when the cell density exceeded 4 × 10⁶ _vcells∙mL⁻¹ (viable cell per mL) working volume (WV). The method validation showed the limit of detection (LOD) for 1.4 L cultures to be 8.86 × 10⁶ _vcells∙mL⁻¹, a viable cell density commonly achieved in fed-batch and the early stages of a perfusion culture. This work suggests that biocalorimetry should be possible to implement at industrial scale to monitor CHO cell cultures. Full article

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19 pages, 1586 KiB

Open AccessArticle

A Soft Sensor for Bioprocess Control Based on Sequential Filtering of Metabolic Heat Signals

by Dan Paulsson, Robert Gustavsson and Carl-Fredrik Mandenius

Sensors 2014, 14(10), 17864-17882; https://doi.org/10.3390/s141017864 - 26 Sep 2014

Cited by 34 | Viewed by 9801

Abstract

Soft sensors are the combination of robust on-line sensor signals with mathematical models for deriving additional process information. Here, we apply this principle to a microbial recombinant protein production process in a bioreactor by exploiting bio-calorimetric methodology. Temperature sensor signals from the cooling system of the bioreactor were used for estimating the metabolic heat of the microbial culture and from that the specific growth rate and active biomass concentration were derived. By applying sequential digital signal filtering, the soft sensor was made more robust for industrial practice with cultures generating low metabolic heat in environments with high noise level. The estimated specific growth rate signal obtained from the three stage sequential filter allowed controlled feeding of substrate during the fed-batch phase of the production process. The biomass and growth rate estimates from the soft sensor were also compared with an alternative sensor probe and a capacitance on-line sensor, for the same variables. The comparison showed similar or better sensitivity and lower variability for the metabolic heat soft sensor suggesting that using permanent temperature sensors of a bioreactor is a realistic and inexpensive alternative for monitoring and control. However, both alternatives are easy to implement in a soft sensor, alone or in parallel. Full article

(This article belongs to the Special Issue Sensors for Bioprocess Monitoring and Control)

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15 pages, 306 KiB

Open AccessReview

Biomedical Use of Isothermal Microcalorimeters

by Olivier Braissant, Dieter Wirz, Beat Göpfert and A.U. Daniels

Sensors 2010, 10(10), 9369-9383; https://doi.org/10.3390/s101009369 - 18 Oct 2010

Cited by 66 | Viewed by 11291

Abstract

Isothermal microcalorimetry is becoming widely used for monitoring biological activities in vitro. Microcalorimeters are now able to measure heat production rates of less than a microwatt. As a result, metabolism and growth of relatively small numbers of cultured bacteria, protozoans, human cells and even small animals can be monitored continuously and extremely accurately at any chosen temperature. Dynamic effects on these organisms of changes in the culture environment—or of additions to it—are easily assessed over periods from hours to days. In addition microcalorimetry is a non-destructive method that does not require much sample preparation. It is also completely passive and thus allows subsequent evaluations of any kind on the undisturbed sample. In this review, we present a basic description of current microcalorimetry instruments and an overview of their use for various biomedical applications. These include detecting infections, evaluating effects of pharmaceutical or antimicrobial agents on cells, monitoring growth of cells harvested for tissue eingineering, and assessing medical and surgical device material physico-chemical stability and cellular biocompatibility. Full article

(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)

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23 pages, 1729 KiB

Open AccessReview

Of Chains and Rings: Synthetic Strategies and Theoretical Investigations for Tuning the Structure of Silver Coordination Compounds and Their Applications

by Tünde Vig Slenters, Jorge L. Sagué, Priscilla S. Brunetto, Stefanie Zuber, Antoine Fleury, Laurent Mirolo, Adeline Y. Robin, Markus Meuwly, Oliver Gordon, Regine Landmann, Alma U. Daniels and Katharina M. Fromm

Materials 2010, 3(5), 3407-3429; https://doi.org/10.3390/ma3053407 - 25 May 2010

Cited by 62 | Viewed by 11781

Abstract

Varying the polyethyleneglycol spacer between two (iso)-nicotinic groups of the ligand systems, a large structural variety of silver coordination compounds was obtained, starting with zero-dimensional ring systems, via one-dimensional chains, helices and double-helices to two-dimensional polycatenanes. Theoretical calculations help to understand their formation and allow predictions in some cases. These structures can be tuned by careful design of the ligand, the use of solvent and the counter ions, influencing also other important properties such as light stability and solubility. The latter is important in the context of biomedical applications, using silver compounds as antimicrobial agents. Full article

(This article belongs to the Special Issue Organometallic Compounds)

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