Special Issue "Biocatalytic Applications in Biotechnology"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Biocatalysis".

Deadline for manuscript submissions: closed (15 August 2020).

Special Issue Editors

Prof. Dr. Emmanuel M. Papamichael
Website
Guest Editor
Enzyme Biotechnology and Genetic Engineering Group, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece
Interests: chemical and enzyme kinetics (homogeneous/heterogeneous reactions); enzymology; enzyme biotechnology; biofuel production; statistical analysis of experimental data; experimental design; computer programming
Special Issues and Collections in MDPI journals
Dr. Panagiota-Yiolanda Stergiou

Guest Editor
Enzyme Biotechnology and Genetic Engineering Group, Department of Chemistry, University of Ioannina, Ioannina 45110, Greece
Interests: biocatalysis; enzyme biotechnology (food biotechnology and biofuel production); experimental design
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Nowadays, the vast increasing demand of novel biotechnological products is supported through the continuous development of biocatalytic applications. As a consequence, the progress of research regarding the enzymatic catalysis in aqueous, non-aqueous, organic (polar or non-polar), and/or non-solvent media is decisive. Experimental design methods, which also may comprise of in silico studies; the design of specific reactors and conditions; reactions of significant chemical and/or biochemical processes, which are relevant to industrial production; enzyme kinetic methods; the investigation of enzymatic mechanisms; and the use of immobilized enzymes and/or microbial cells on various inert matrices are importantly useful. A plethora of enzymes of several classes, which may potentially be used as biocatalysts in biotechnological applications, are available today. Among these enzymes, the more common are oxidoreductases (e.g., laccase, catalase, glucose oxidase, etc.), hydrolases (e.g., amylases, lipases, proteases, amidases, cellulases, esterases, etc.), isopmerases (e.g., epimerases, topoisomerases, mutases, etc.), and others. By means of the aforementioned biocatalysts and the utilization of specific biotechnological methods, important, cost-effective, sustainable, and environmentally friendly processes have been applied for the synthesis and/or the conversion of a huge amount of market-required products.

Prof. Dr. Emmanuel M. Papamichael
Dr. Panagiota-Yiolanda Stergiou
Guest Editors

Manuscript Submission Information

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Keywords

  • Enzymatic catalysis
  • Biocatalysis
  • Biotechnological applications
  • In silico simulations
  • Experimental design
  • Reactor design
  • Process optimization
  • Immobilized enzymes
  • Whole cell biocatalysis

Published Papers (15 papers)

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Research

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Open AccessArticle
Regioselective Hydroxylation of Rhododendrol by CYP102A1 and Tyrosinase
Catalysts 2020, 10(10), 1114; https://doi.org/10.3390/catal10101114 - 25 Sep 2020
Abstract
Rhododendrol (RD) is a naturally occurring phenolic compound found in many plants. Tyrosinase (Ty) converts RD to RD-catechol and subsequently RD-quinone via two-step oxidation reactions, after which RD-melanin forms spontaneously from RD-quinone. RD is cytotoxic in melanocytes and lung cancer cells, but not [...] Read more.
Rhododendrol (RD) is a naturally occurring phenolic compound found in many plants. Tyrosinase (Ty) converts RD to RD-catechol and subsequently RD-quinone via two-step oxidation reactions, after which RD-melanin forms spontaneously from RD-quinone. RD is cytotoxic in melanocytes and lung cancer cells, but not in keratinocytes and fibroblasts. However, the function of RD metabolites has not been possible to investigate due to the lack of available high purity metabolites. In this study, an enzymatic strategy for RD-catechol production was devised using engineered cytochrome P450 102A1 (CYP102A1) and Ty, and the product was analyzed using high-performance liquid chromatography (HPLC), LC-MS, and NMR spectroscopy. Engineered CYP102A1 regioselectively produced RD-catechol via hydroxylation at the ortho position of RD. Although RD-quinone was subsequently formed by two step oxidation in Ty catalyzed reactions, L-ascorbic acid (LAA) inhibited RD-quinone formation and contributed to regioselective production of RD-catechol. When LAA was present, the productivity of RD-catechol by Ty was 5.3-fold higher than that by engineered CYP102A1. These results indicate that engineered CYP102A1 and Ty can be used as effective biocatalysts to produce hydroxylated products, and Ty is a more cost-effective biocatalyst for industrial applications than engineered CYP102A1. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Exploring Metagenomic Enzymes: A Novel Esterase Useful for Short-Chain Ester Synthesis
Catalysts 2020, 10(10), 1100; https://doi.org/10.3390/catal10101100 - 23 Sep 2020
Abstract
Enzyme-mediated esterification reactions can be a promising alternative to produce esters of commercial interest, replacing conventional chemical processes. The aim of this work was to verify the potential of an esterase for ester synthesis. For that, recombinant lipolytic enzyme EST5 was purified and [...] Read more.
Enzyme-mediated esterification reactions can be a promising alternative to produce esters of commercial interest, replacing conventional chemical processes. The aim of this work was to verify the potential of an esterase for ester synthesis. For that, recombinant lipolytic enzyme EST5 was purified and presented higher activity at pH 7.5, 45 °C, with a Tm of 47 °C. Also, the enzyme remained at least 50% active at low temperatures and exhibited broad substrate specificity toward p-nitrophenol esters with highest activity for p-nitrophenyl valerate with a Kcat/Km of 1533 s−1 mM−1. This esterase exerted great properties that make it useful for industrial applications, since EST5 remained stable in the presence of up to 10% methanol and 20% dimethyl sulfoxide. Also, preliminary studies in esterification reactions for the synthesis of methyl butyrate led to a specific activity of 127.04 U·mg−1. The enzyme showed higher esterification activity compared to other literature results, including commercial enzymes such as LIP4 and CL of Candida rugosa assayed with butyric acid and propanol which showed esterification activity of 86.5 and 15.83 U·mg−1, respectively. In conclusion, EST5 has potential for synthesis of flavor esters, providing a concept for its application in biotechnological processes. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Counterbalance of Stability and Activity Observed for Thermostable Transaminase from Thermobaculum terrenum in the Presence of Organic Solvents
Catalysts 2020, 10(9), 1024; https://doi.org/10.3390/catal10091024 - 06 Sep 2020
Abstract
Pyridoxal-5’-phosphate-dependent transaminases catalyze stereoselective amination of organic compounds and are highly important for industrial applications. Catalysis by transaminases often requires organic solvents to increase the solubility of reactants. However, natural transaminases are prone to inactivation in the presence of water-miscible organic solvents. Here, [...] Read more.
Pyridoxal-5’-phosphate-dependent transaminases catalyze stereoselective amination of organic compounds and are highly important for industrial applications. Catalysis by transaminases often requires organic solvents to increase the solubility of reactants. However, natural transaminases are prone to inactivation in the presence of water-miscible organic solvents. Here, we present the solvent tolerant thermostable transaminase from Thermobaculum terrenum (TaTT) that catalyzes transamination between L-leucine and alpha-ketoglutarate with an optimum at 75 °C and increases the activity ~1.8-fold upon addition of 15% dimethyl sulfoxide or 15% methanol at high but suboptimal temperature, 50 °C. The enhancement of the activity correlates with a decrease in the thermal denaturation midpoint temperature. The blue-shift of tryptophan fluorescence suggested that solvent molecules penetrate the hydration shell of the enzyme. Analysis of hydrogen bonds in the TaTT dimer revealed a high number of salt bridges and surface hydrogen bonds formed by backbone atoms. The latter are sensitive to the presence of organic solvents; they rearrange, conferring the relaxation of some constraints inherent to a thermostable enzyme at low temperatures. Our data support the idea that the counterbalance of stability and activity is crucial for the catalysis under given conditions; the obtained results may be useful for fine-tuning biocatalyst efficiency. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessFeature PaperArticle
Kinetic Analysis of the Lipase-Catalyzed Hydrolysis of Erythritol and Pentaerythritol Fatty Acid Esters: A Biotechnological Application for Making Low-Calorie Healthy Food Alternatives
Catalysts 2020, 10(9), 965; https://doi.org/10.3390/catal10090965 - 23 Aug 2020
Abstract
Contemporary consumers demand healthier and more nourishing food, and thus, alternative foods that are low-calorie in fats and/or sugars are preferred. These desired properties may be attained by substituting the fatty acid esters of erythritol and pentaerythritol due to their antioxidant action and [...] Read more.
Contemporary consumers demand healthier and more nourishing food, and thus, alternative foods that are low-calorie in fats and/or sugars are preferred. These desired properties may be attained by substituting the fatty acid esters of erythritol and pentaerythritol due to their antioxidant action and low toxicity for humans. In this work, the catalyzed hydrolysis of five fatty acid tetraesters of erythritol and/or pentaerythritol by both porcine pancreas type VI-s lipase (PPL) and Candida antarctica lipase-B (CALB) were studied kinetically. In all cases, except the hydrolysis of pentaerythritol tetrastearate by CALB, Michaelis–Menten kinetics were observed. In addition, the pKa values of the fatty acids released due to the catalyzed hydrolysis of the studied tetraesters by CALB were estimated. In the course of the aforementioned procedures, it was found that the CALB-catalyzed hydrolysis was incomplete to various degrees among four of the five studied tetraesters (excluding erythritol tetraoleate), and one or more estimated apparent pKa values were obtained. These results are novel, and by means of applied methodology, they reveal that erythritol and/or pentaerythritol tetraesters of medium- and long-chain fatty acids are suitable candidates for use as beneficial alternatives to butter and/or sweeteners. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Influence of Carrier Structure and Physicochemical Factors on Immobilisation of Fungal Laccase in Terms of Bisphenol A Removal
Catalysts 2020, 10(9), 951; https://doi.org/10.3390/catal10090951 - 20 Aug 2020
Abstract
Laccase from Pleurotus ostreatus was immobilised on porous Purolite® carriers and amino-functionalised ultrafiltration membranes. The results indicated a correlation between the carrier structure and the activity of laccase immobilised thereon. The highest activity was obtained for carriers characterised by a small particle [...] Read more.
Laccase from Pleurotus ostreatus was immobilised on porous Purolite® carriers and amino-functionalised ultrafiltration membranes. The results indicated a correlation between the carrier structure and the activity of laccase immobilised thereon. The highest activity was obtained for carriers characterised by a small particle size and a larger pore diameter (the porous carriers with an additional spacer (C2 and C6) and octadecyl methacrylate beads with immobilised laccase activity of 5.34 U/g, 2.12 U/g and 7.43 U/g, respectively. The conditions of immobilisation and storage of immobilised laccase were modified to improve laccase activity in terms of bisphenol A transformation. The highest laccase immobilisation activity was obtained on small bead carriers with a large diameter of pores incubated in 0.1 M phosphate buffer pH 7 and for immobilisation time of 3 h at 22 °C. The immobilised LAC was stable for four weeks maintaining 80–90% of its initial activity in the case of the best C2, C6, and C18 carriers. The immobilised laccase transformed 10 mg/L of BPA in 45% efficiency and decreased its toxicity 3-fold in the Microtox tests. The effectiveness of BPA transformation, and the legitimacy of conducting this process due to the reduction of the toxicity of the resulting reaction products have been demonstrated. Reusability of immobilised LAC has been proven during BPA removal in 10 subsequent batches. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Estimating the Product Inhibition Constant from Enzyme Kinetic Equations Using the Direct Linear Plot Method in One-Stage Treatment
Catalysts 2020, 10(8), 853; https://doi.org/10.3390/catal10080853 - 01 Aug 2020
Abstract
A direct linear plot was applied to estimate kinetic constants using the product’s competitive inhibition equation. The challenge consisted of estimating three kinetic constants, Vmax, Km, and Kp, using two independent variables, substrates, and product concentrations, in [...] Read more.
A direct linear plot was applied to estimate kinetic constants using the product’s competitive inhibition equation. The challenge consisted of estimating three kinetic constants, Vmax, Km, and Kp, using two independent variables, substrates, and product concentrations, in just one stage of mathematical treatment. The method consisted of combining three initial reaction rate data and avoiding the use of the same three product concentrations (otherwise, this would result in a mathematical indetermination). The direct linear plot method was highly superior to the least-squares method in terms of accuracy and robustness, even under the addition of error. The direct linear plot method is a reliable and robust method that can be applied to estimate Kp in inhibition studies in pharmaceutical and biotechnological areas. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Polymer-Assisted Biocatalysis: Polyamide 4 Microparticles as Promising Carriers of Enzymatic Function
Catalysts 2020, 10(7), 767; https://doi.org/10.3390/catal10070767 - 09 Jul 2020
Abstract
This study reports a new strategy for enzyme immobilization based on passive immobilization in neat and magnetically responsive polyamide 4 (PA4) highly porous particles. The microsized particulate supports were synthesized by low-temperature activated anionic ring-opening polymerization. The enzyme of choice was laccase from [...] Read more.
This study reports a new strategy for enzyme immobilization based on passive immobilization in neat and magnetically responsive polyamide 4 (PA4) highly porous particles. The microsized particulate supports were synthesized by low-temperature activated anionic ring-opening polymerization. The enzyme of choice was laccase from Trametes versicolor and was immobilized by either adsorption on prefabricated PA4 microparticles ([email protected]) or by physical in situ entrapment during the PA4 synthesis ([email protected]). The surface topography of all PA4 particulate supports and laccase conjugates, as well as their chemical and physical structure, were studied by microscopic, spectral, thermal, and synchrotron WAXS/SAXS methods. The laccase content and activity in each conjugate were determined by complementary spectral and enzyme activity measurements. [email protected] samples displayed >93% enzyme retention after five incubation cycles in an aqueous medium, and the [email protected] series retained ca. 60% of the laccase. The newly synthesized PA4-laccase complexes were successfully used in dyestuff decolorization aiming at potential applications in effluent remediation. All of them displayed excellent decolorization of positively charged dyestuffs reaching ~100% in 15 min. With negative dyes after 24 h the decolorization reached 55% for [email protected] and 85% for [email protected] A second consecutive decolorization test revealed only a 5–10% decrease in effectiveness indicating the reusability potential of the laccase-PA4 conjugates. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Engineering of Bifunctional Enzymes with Uricase and Peroxidase Activities for Simple and Rapid Quantification of Uric Acid in Biological Samples
Catalysts 2020, 10(4), 428; https://doi.org/10.3390/catal10040428 - 14 Apr 2020
Abstract
Serum uric acid (SUA) is an important biomarker for prognosis and management of gout and other diseases. The development of a low-cost, simple, rapid and reliable assay for SUA detection is of great importance. In the present study, to save the cost of [...] Read more.
Serum uric acid (SUA) is an important biomarker for prognosis and management of gout and other diseases. The development of a low-cost, simple, rapid and reliable assay for SUA detection is of great importance. In the present study, to save the cost of enzyme production and to shorten the reaction time for uric acid quantification, bifunctional proteins with uricase and peroxidase activities were engineered. In-frame fusion of Candida utilis uricase (CUOX) and Vitreoscilla hemoglobin (VHb) resulted in two versions of the bifunctional protein, CUOX-VHb (CV) and VHb-CUOX (VC). To our knowledge, this is the first report to describe the production of proteins with uricase and peroxidase activities. Based on the measurement of the initial rates of the coupled reaction (between uricase and peroxidase), CV was proven to be the most efficient enzyme followed by VC and native enzymes (CUOX+VHb), respectively. CV was further applied for the development of an assay for colorimetric detection of SUA, which was based on VHb-catalyzed oxidation of Amplex Red in the presence of hydrogen peroxide (H2O2). Under the optimized conditions, the assay exhibited a linear relationship between the absorbance and UA concentration over the range of 2.5 to 50 μM, with a detection limit of 1 μM. In addition, the assay can be performed at a single pH (8.0) so adjustment of the pH for peroxidase activity was not required. This advantage helped to further reduce costs and time. The developed assay was also successfully applied to detect UA in pooled human serum with the recoveries over 94.8%. These results suggest that the proposed assay holds great potential for clinical application. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Rigorous Model-Based Design and Experimental Verification of Enzyme-Catalyzed Carboligation under Enzyme Inactivation
Catalysts 2020, 10(1), 96; https://doi.org/10.3390/catal10010096 - 09 Jan 2020
Cited by 1
Abstract
Enzyme catalyzed reactions are complex reactions due to the interplay of the enzyme, the reactants, and the operating conditions. To handle this complexity systematically and make use of a design space without technical restrictions, we apply the model based approach of elementary process [...] Read more.
Enzyme catalyzed reactions are complex reactions due to the interplay of the enzyme, the reactants, and the operating conditions. To handle this complexity systematically and make use of a design space without technical restrictions, we apply the model based approach of elementary process functions (EPF) for selecting the best process design for enzyme catalysis problems. As a representative case study, we consider the carboligation of propanal and benzaldehyde catalyzed by benzaldehyde lyase from Pseudomonas fluorescens (PfBAL) to produce (R)-2-hydroxy-1-phenylbutan-1-one, because of the substrate dependent reaction rates and the challenging substrate dependent PfBAL inactivation. The apparatus independent EPF concept optimizes the material fluxes influencing the enzyme catalyzed reaction for the given process intensification scenarios. The final product concentration is improved by 13% with the optimized feeding rates, and the optimization results are verified experimentally. In general, the rigorous model driven approach could lead to selecting the best existing reactor, designing novel reactors for enzyme catalysis, and combining protein engineering and process systems engineering concepts. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Conversion of Shrimp Head Waste for Production of a Thermotolerant, Detergent-Stable, Alkaline Protease by Paenibacillus sp.
Catalysts 2019, 9(10), 798; https://doi.org/10.3390/catal9100798 - 24 Sep 2019
Cited by 6
Abstract
Fishery processing by-products have been of great interest to researchers due to their beneficial applications in many fields. In this study, five types of marine by-products, including demineralized crab shell, demineralized shrimp shell, shrimp head, shrimp shell, and squid pen, provided sources of [...] Read more.
Fishery processing by-products have been of great interest to researchers due to their beneficial applications in many fields. In this study, five types of marine by-products, including demineralized crab shell, demineralized shrimp shell, shrimp head, shrimp shell, and squid pen, provided sources of carbon and nitrogen nutrition by producing a protease from Paenibacillus sp. TKU047. Strain TKU047 demonstrated the highest protease productivity (2.98 U/mL) when cultured for two days on a medium containing 0.5% of shrimp head powder (SHP). The mass of TKU047 protease was determined to be 32 kDa (approximately). TKU047 protease displayed optimal activity at 70–80 °C and pH 9, with a pH range of stability from 6 to 11. TKU047 protease also showed stability in solutions containing surfactants and detergents. Based on its excellent properties, Paenibacillus sp. TKU047 protease may be a feasible candidate for inclusion in laundry detergents. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Catalytic Activities of Multimeric G-Quadruplex DNAzymes
Catalysts 2019, 9(7), 613; https://doi.org/10.3390/catal9070613 - 19 Jul 2019
Cited by 4
Abstract
G-quadruplex DNAzymes are short DNA aptamers with repeating G4 quartets bound in a non-covalent complex with hemin. These G4/Hemin structures exhibit versatile peroxidase-like catalytic activity with a wide range of potential applications in biosensing and biotechnology. Current efforts are aimed at gaining a [...] Read more.
G-quadruplex DNAzymes are short DNA aptamers with repeating G4 quartets bound in a non-covalent complex with hemin. These G4/Hemin structures exhibit versatile peroxidase-like catalytic activity with a wide range of potential applications in biosensing and biotechnology. Current efforts are aimed at gaining a better understanding of the molecular mechanism of DNAzyme catalysis as well as devising strategies for improving their catalytic efficiency. Multimerisation of discrete units of G-quadruplexes to form multivalent DNAzyes is an emerging design strategy aimed at enhancing the peroxidase activities of DNAzymes. While this approach holds promise of generating more active multivalent G-quadruplex DNAzymes, few examples have been studied and it is not clear what factors determine the enhancement of catalytic activities of multimeric DNAzymes. In this study, we report the design and characterisation of multimers of five G-quadruplex sequences (AS1411, Bcl-2, c-MYC, PS5.M and PS2.M). Our results show that multimerisation of G-quadruplexes that form parallel structure (AS1411, Bcl-2, c-MYC) leads to significant rate enhancements characteristic of cooperative and/or synergistic interactions between the monomeric units. In contrast, multimerisation of DNA sequences that form non-parallel structures (PS5.M and PS2.M) did not exhibit similar levels of synergistic increase in activities. These results show that design of multivalent G4/Hemin structures could lead to a new set of versatile and efficient DNAzymes with enhanced capacity to catalyse peroxidase-mimic reactions. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Biotransformation with a New Acinetobacter sp. Isolate for Highly Enantioselective Synthesis of a Chiral Intermediate of Miconazole
Catalysts 2019, 9(5), 462; https://doi.org/10.3390/catal9050462 - 20 May 2019
Cited by 3
Abstract
(R)-2-Chloro-1-(2,4-dichlorophenyl) ethanol is a chiral intermediate of the antifungal agent Miconazole. A bacterial strain, ZJPH1806, capable of the biocatalysis of 2-chloro-1-(2,4-dichlorophenyl) ethanone, to (R)-2-chloro-1-(2,4-dichlorophenyl) ethanol with highly stereoselectivity was isolated from a soil sample. It was identified as the [...] Read more.
(R)-2-Chloro-1-(2,4-dichlorophenyl) ethanol is a chiral intermediate of the antifungal agent Miconazole. A bacterial strain, ZJPH1806, capable of the biocatalysis of 2-chloro-1-(2,4-dichlorophenyl) ethanone, to (R)-2-chloro-1-(2,4-dichlorophenyl) ethanol with highly stereoselectivity was isolated from a soil sample. It was identified as the Acinetobacter sp., according to its morphological observation, physiological-biochemical identification, and 16S rDNA sequence analysis. After optimizing the key reaction conditions, it was demonstrated that the bioreduction of 2-chloro-1-(2,4-dichlorophenyl) ethanone was effectively transformed at relatively high conversion temperatures, along with glycerol as cosubstrate in coenzyme regeneration. The asymmetric reduction of the substrate had reached 83.2% yield with an enantiomeric excess (ee) of greater than 99.9% at 2 g/L of 2-chloro-1-(2,4-dichlorophenyl) ethanone; the reaction was conducted at 40 °C for 26 h using resting cells of the Acinetobacter sp. ZJPH1806 as the biocatalyst. The yield had increased by nearly 2.9-fold (from 28.6% to 83.2%). In the present study, a simple and novel whole-cell-mediated biocatalytic route was applied for the highly enantioselective synthesis of (R)-2-chloro-1-(2,4-dichlorophenyl) ethanol, which allowed the production of a valuable chiral intermediate method to be transformed into a versatile tool for drug synthesis. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessArticle
Enhancing Enzymatic Properties of Endoglucanase I Enzyme from Trichoderma Reesei via Swapping from Cellobiohydrolase I Enzyme
Catalysts 2019, 9(2), 130; https://doi.org/10.3390/catal9020130 - 01 Feb 2019
Cited by 2
Abstract
Utilizing plant-based materials as a biofuel source is an increasingly popular attempt to redesign the global energy cycle. This endeavour underlines the potential of cellulase enzymes for green energy production and requires the structural and functional engineering of natural enzymes to enhance their [...] Read more.
Utilizing plant-based materials as a biofuel source is an increasingly popular attempt to redesign the global energy cycle. This endeavour underlines the potential of cellulase enzymes for green energy production and requires the structural and functional engineering of natural enzymes to enhance their utilization. In this work, we aimed to engineer enzymatic and functional properties of Endoglucanase I (EGI) by swapping the Ala43-Gly83 region of Cellobiohydrolase I (CBHI) from Trichoderma reesei. Herein, we report the enhanced enzymatic activity and improved thermal stability of the engineered enzyme, called EGI_swapped, compared to EGI. The difference in the enzymatic activity profile of EGI_swapped and the EGI enzymes became more pronounced upon increasing metal-ion concentrations in the reaction media. Notably, the engineered enzyme retained a considerable level of enzymatic activity after thermal incubation for 90 min at 70 °C while EGI completely lost its enzymatic activity. Circular Dichroism spectroscopy studies revealed distinctive conformational and thermal susceptibility differences between EGI_swapped and EGI enzymes, confirming the improved structural integrity of the swapped enzyme. This study highlights the importance of swapping the metal-ion coordination region in the engineering of EGI enzyme for enhanced structural and thermal stability. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Review

Jump to: Research

Open AccessFeature PaperReview
Bioproduction of Isoprenoids and Other Secondary Metabolites Using Methanotrophic Bacteria as an Alternative Microbial Cell Factory Option: Current Stage and Future Aspects
Catalysts 2019, 9(11), 883; https://doi.org/10.3390/catal9110883 - 24 Oct 2019
Cited by 3
Abstract
Methane is a promising carbon feedstock for industrial biomanufacturing because of its low price and high abundance. Recent advances in metabolic engineering and systems biology in methanotrophs have made it possible to produce a variety of value-added compounds from methane, including secondary metabolites. [...] Read more.
Methane is a promising carbon feedstock for industrial biomanufacturing because of its low price and high abundance. Recent advances in metabolic engineering and systems biology in methanotrophs have made it possible to produce a variety of value-added compounds from methane, including secondary metabolites. Isoprenoids are one of the largest family of secondary metabolites and have many useful industrial applications. In this review, we highlight the current efforts invested to methanotrophs for the production of isoprenoids and other secondary metabolites, including riboflavin and ectoine. The future outlook for improving secondary metabolites production (especially of isoprenoids) using metabolic engineering of methanotrophs is also discussed. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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Open AccessReview
Microbial Phosphotriesterase: Structure, Function, and Biotechnological Applications
Catalysts 2019, 9(8), 671; https://doi.org/10.3390/catal9080671 - 07 Aug 2019
Cited by 2
Abstract
The role of phosphotriesterase as an enzyme which is able to hydrolyze organophosphate compounds cannot be disputed. Contamination by organophosphate (OP) compounds in the environment is alarming, and even more worrying is the toxicity of this compound, which affects the nervous system. Thus, [...] Read more.
The role of phosphotriesterase as an enzyme which is able to hydrolyze organophosphate compounds cannot be disputed. Contamination by organophosphate (OP) compounds in the environment is alarming, and even more worrying is the toxicity of this compound, which affects the nervous system. Thus, it is important to find a safer way to detoxify, detect and recuperate from the toxicity effects of this compound. Phosphotriesterases (PTEs) are mostly isolated from soil bacteria and are classified as metalloenzymes or metal-dependent enzymes that contain bimetals at the active site. There are three separate pockets to accommodate the substrate into the active site of each PTE. This enzyme generally shows a high catalytic activity towards phosphotriesters. These microbial enzymes are robust and easy to manipulate. Currently, PTEs are widely studied for the detection, detoxification, and enzyme therapies for OP compound poisoning incidents. The discovery and understanding of PTEs would pave ways for greener approaches in biotechnological applications and to solve environmental issues relating to OP contamination. Full article
(This article belongs to the Special Issue Biocatalytic Applications in Biotechnology)
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