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Biocatalysts and Their Environmental Applications

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

Deadline for manuscript submissions: closed (20 August 2021) | Viewed by 33992

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Prof. Dr. Baiyu Zhang

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Guest Editor

Northern Region Persistent Organic Pollution Control (NRPOP) Laboratory, Memorial University of Newfoundland, St John's, Canada
Interests: magnetic nano-biocatalysts; bioremediation

Dr. Bo Liu

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Guest Editor

Department of Civil Engineering, Memorial University, St. John's, NL, Canada
Interests: photocatalytic oxidation; nanomaterials; energy recovery from water and wastewater treatment; emerging contaminants; system design
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Special Issue Information

Dear Colleagues,

Biocatalysts, including a special species of microorganisms, and their enzymes have been widely accepted in many industrial processes, because they are less-toxic, environment friendly, and energy-conserving alternatives compared with chemical catalysts. Whole-cell biocatalysts have advantages (e.g., the elimination of the need for protein purification) and disadvantages (e.g., the reduced reaction rates) over purified enzymes.

The reaction rates in whole-cell biocatalysts can be achieved through many strategies, such as increasing the permeability of the cell membrane by chemical reactions; increasing the concentration of the enzyme within the cell by enzyme overexpression in a bacterial host; and stabilizing and improving the biocatalyst function by flocculation, surface immobilization, and encapsulation. Up unil now, whole-cell biocatalysts have been applied to environmental fields for enhancing transformation and degradation processes. Meanwhile, the growth synthetic biology and protein engineering greatly facilitates the development of novel biocatalysts specifically relevant to the production of fine chemicals for improving bulk enzymes for industry and the products involved in waste reduction and detoxification. Magnetic nano-biocatalysts are also a rapidly growing field for the development of sustainable and green processes.

This Special Issue will focus on different methodologies for biocatalyst development/improvement, and a large range of reactions employed in environmental remediation processes catalyzed by whole-cells and isolated enzymes. Persistent, toxic/carcinogenic, and/or bio-accumulative contaminants in multiple (air/liquid/solid) phases will be tackled. It aims to compile a set of manuscripts that cover the recent progress and trends in biocatalysts, and their environmental applications.

Dr. Dr. Baiyu Zhang
Dr. Bo Liu
Guest Editors

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Keywords

whole cell biocatalysts
enzymes
magnetic nano-biocatalysts
environmental applications
contaminant transformation and degradation

Published Papers (9 papers)

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Research

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11 pages, 1685 KiB

Open AccessArticle

The Biocatalytic Production of 3-Hydroxypropionaldehyde and Evaluation of Its Stability

by Jung-Hyun Ju, Sang-Gyu Jeon, Kyung Min Lee, Sun-Yeon Heo, Min-Soo Kim, Chul-Ho Kim and Baek-Rock Oh

Catalysts 2021, 11(10), 1139; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11101139 - 23 Sep 2021

Cited by 9 | Viewed by 2245

Abstract

3-Hydroxypropionaldehyde (3-HPA, reuterin) is a broad-spectrum natural antimicrobial agent used in the food industry and other fields. The low yield from the industrial production of 3-HPA using Lactobacillus reuteri and the spontaneous conversion of 3-HPA to acrolein have limited its more widespread use. We isolated L. reuteri BR201 as a biocatalyst for 3-HPA production and confirmed the effect of each factor in the two-step procedure for 3-HPA bioconversion. After initial cultivation for 8 h (late exponential phase), this isolate produced 378 mM of 3-HPA in 1 h at a concentration of OD_{600 nm} 100, 30 °C, and an initial glycerol concentration of 500 mM. This is the highest reported biocatalytic yield of 3-HPA from a glycerol aqueous solution without additives. We confirmed that 4 mM of 3-HPA had antimicrobial activity against five pathogens. The degradation of 3-HPA to acrolein was greater at high temperatures, and there was little degradation when 3-HPA was maintained at 4 °C for 4 weeks. Our results may be useful for future applications of 3-HPA. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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17 pages, 2800 KiB

Open AccessArticle

The Sustainable Production of a Novel Laccase from Wheat Bran by Bordetella sp. JWO16: Toward a Total Environment

by John Onolame Unuofin

Catalysts 2021, 11(6), 677; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11060677 - 26 May 2021

Cited by 4 | Viewed by 1807

Abstract

Laccase is increasingly adopted in diverse industrial and environmental applications, due to its readily accessible requirements for efficient catalytic synthesis and biotransformation of chemicals. However, it is perceived that its industrial production might incur some unfavorable overhead, which leads to expensive market products, and the corresponding negative environmental feedback, due to the use of capital-intensive and precarious chemicals. To this end, this study was designed to evaluate the performance indicators of the valorization of wheat bran by a novel Jb1b laccase and its subsequent application in waste minimization and water management, on a laboratory scale. Optimal Jb1b laccase was produced in submerged fermentation medium containing wheat bran, an agroindustrial residue, through response surface methodology (RSM) algorithm, and was applied in dye decolorization and denim bioscouring, respectively. Results showed that the resultant enzyme manifested unique biochemical properties, such as enhanced tolerance at certain physicochemical conditions, with a residual activity of at least ca. 76%. Furthermore, phenomenally high concentrations of synthetic dyes (0.2% w v⁻¹) were decolorized over 56 h, and a 6 h mediator-supported simultaneous denim bleaching and decolorization of wash effluent was observed. The sustainability of the production and application processes were inferred from the reusability of the fermentation sludge as a potential biofertilizer, with subsequent prospects for the biostimulation and bioaugmentation of contaminated soils, whereas the decolorized water could be adopted for other uses, amongst which horticulture and forestry are typical examples. These phenomena therefore authenticate the favorable environmental feedbacks and overhead realized in this present study. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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13 pages, 12255 KiB

Open AccessArticle

Catalytic Performance of a Recombinant Organophosphate-Hydrolyzing Phosphotriesterase from Brevundimonas diminuta in the Presence of Surfactants

by Meng-Chun Chi, Ting-Yu Liao, Min-Guan Lin, Long-Liu Lin and Tzu-Fan Wang

Catalysts 2021, 11(5), 597; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050597 - 05 May 2021

Cited by 3 | Viewed by 1867

Abstract

Phosphotriestease (PTE), also known as parathion hydrolase, has the ability to hydrolyze the triester linkage of organophosphate (OP) pesticides and chemical warfare nerve agents, making it highly suitable for environment remediation. Here, we studied the effects of various surfactants and commercial detergents on the esterase activity of a recombinant PTE (His₆-tagged BdPTE) from Brevundimonas diminuta. Enzymatic assays indicated that His₆-tagged BdPTE was severely inactivated by SDS even at lower concentrations and, conversely, the other three surfactants (Triton X-100, Tween 20, and Tween 80) had a stimulatory effect on the activity, especially at a pre-incubating temperature of 40 °C. The enzyme exhibited a good compatibility with several commercial detergents, such as Dr. Formula^® and Sugar Bubble^®. The evolution results of pyrene fluorescence spectroscopy showed that the enzyme molecules participated in the formation of SDS micelles but did not alter the property of SDS micelles above the critical micelle concentration (CMC). Structural analyses revealed a significant change in the enzyme’s secondary structure in the presence of SDS. Through the use of the intentionally fenthion-contaminated Chinese cabbage leaves as the model experiment, enzyme–Joy^® washer solution could remove the pesticide from the contaminated sample more efficiently than detergent alone. Overall, our data promote a better understanding of the links between the esterase activity of His₆-tagged BdPTE and surfactants, and they offer valuable information about its potential applications in liquid detergent formulations. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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10 pages, 1767 KiB

Open AccessArticle

Thermal Inactivation of Butyrylcholinesterase in Starch and Gelatin Gels

by Victoria I. Lonshakova-Mukina, Elena N. Esimbekova and Valentina A. Kratasyuk

Catalysts 2021, 11(4), 492; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11040492 - 13 Apr 2021

Cited by 7 | Viewed by 3303

Abstract

The present study demonstrates a simple approach to enhancing thermal stability of butyrylcholinesterase (BChE) by using natural polymers. Analysis of thermal inactivation of the tetrameric BChE in starch and gelatin gels at 50–64 °C showed that thermal inactivation followed second-order kinetics and involved two alternating processes of BChE inactivation, which occurred at different rates (fast and slow processes). The activation enthalpy ΔH^# and the activation entropy ΔS^# for BChE in starch and gelatin gels were evaluated. The values of ΔH^# for the fast and the slow thermal inactivation of BChE in starch gel were 61 ± 3, and 22 ± 2 kcal/mol, respectively, and the values of ΔS^# were 136 ± 12 and −2.03 ± 0.05 cal∙K⁻¹∙mol⁻¹, respectively. Likewise, the values of ΔH^# for BChE in gelatin gel were 58 ± 6 and 109 ± 11 kcal/mol, and the values of ΔS^# were 149 ± 16 and 262 ± 21 cal∙K⁻¹∙mol⁻¹, respectively. The values of the activation parameters obtained in this study suggest that starch gel produced a stronger stabilizing effect on BChE exposed to elevated temperatures over long periods compared with gelatin gel. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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13 pages, 2297 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Multi-Scale Biosurfactant Production by Bacillus subtilis Using Tuna Fish Waste as Substrate

by Jiheng Hu, Jie Luo, Zhiwen Zhu, Bing Chen, Xudong Ye, Peng Zhu and Baiyu Zhang

Catalysts 2021, 11(4), 456; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11040456 - 01 Apr 2021

Cited by 22 | Viewed by 3784

Abstract

As one of the most effective biosurfactants reported to date, lipopeptides exhibit attractive surface and biological activities and have the great potential to serve as biocatalysts. Low yield, high cost of production, and purification hinder the large-scale applications of lipopeptides. Utilization of waste materials as low-cost substrates for the growth of biosurfactant producers has emerged as a feasible solution for economical biosurfactant production. In this study, fish peptone was generated through enzyme hydrolyzation of smashed tuna (Katsuwonus pelamis). Biosurfactant (mainly surfactin) production by Bacillus subtilis ATCC 21332 was further evaluated and optimized using the generated fish peptone as a comprehensive substrate. The optimized production conduction was continuously assessed in a 7 L batch-scale and 100 L pilot-scale fermenter, exploring the possibility for a large-scale surfactin production. The results showed that Bacillus subtilis ATCC 21332 could effectively use the fish waste peptones for surfactin production. The highest surfactin productivity achieved in the pilot-scale experiments was 274 mg/L. The experimental results shed light on the further production of surfactins at scales using fish wastes as an economical substrate. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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11 pages, 1130 KiB

Open AccessArticle

Enhanced Hydrocarbons Biodegradation at Deep-Sea Hydrostatic Pressure with Microbial Electrochemical Snorkels

by Federico Aulenta, Enza Palma, Ugo Marzocchi, Carolina Cruz Viggi, Simona Rossetti and Alberto Scoma

Catalysts 2021, 11(2), 263; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11020263 - 16 Feb 2021

Cited by 9 | Viewed by 2835

Abstract

In anaerobic sediments, microbial degradation of petroleum hydrocarbons is limited by the rapid depletion of electron acceptors (e.g., ferric oxide, sulfate) and accumulation of toxic metabolites (e.g., sulfide, following sulfate reduction). Deep-sea sediments are increasingly impacted by oil contamination, and the elevated hydrostatic pressure (HP) they are subjected to represents an additional limitation for microbial metabolism. While the use of electrodes to support electrobioremediation in oil-contaminated sediments has been described, there is no evidence on their applicability for deep-sea sediments. Here, we tested a passive bioelectrochemical system named ”oil-spill snorkel” with two crude oils carrying different alkane contents (4 vs. 15%), at increased or ambient HP (10 vs. 0.1 MPa). Snorkels enhanced alkanes biodegradation at both 10 and 0.1 MPa within only seven weeks, as compared to nonconductive glass controls. Microprofiles in anaerobic, contaminated sediments indicated that snorkels kept sulfide concentration to low titers. Bulk-sediment analysis confirmed that sulfide oxidation by snorkels largely regenerated sulfate. Hence, the sole application of snorkels could eliminate a toxicity factor and replenish a spent electron acceptor at increased HP. Both aspects are crucial for petroleum decontamination of the deep sea, a remote environment featured by low metabolic activity. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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15 pages, 2364 KiB

Open AccessArticle

Facile One-Pot Immobilization of a Novel Thermostable Carboxylesterase from Geobacillus uzenensis for Continuous Pesticide Degradation in a Packed-Bed Column Reactor

by Xiaohui Yang, Xudong Tang, Fengying Dong, Lin Lin, Wei Wei and Dongzhi Wei

Catalysts 2020, 10(5), 518; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10050518 - 07 May 2020

Cited by 5 | Viewed by 2188

Abstract

The novel carboxylesterase gene (est₇₄₁) was cloned from Geobacillus uzenensis. The optimal pH and temperature of Est₇₄₁ were 8.0 and 50 °C. Through site-directed mutation, the optimum temperature of the mutant M160K(Est_M160K) was increased from 50 to 60 °C, and showed enhanced T_1/2 of 2.5 h at 70 °C in comparison to the wild type (1.3 h). Est_M160K was successfully expressed Pichia pastoris and Est_M160K fermentation broth was directly immobilized on epoxy-functionalized supports via a one-pot strategy to obtain the immobilized enzyme lx-Est_M160K. Additionally, lx-Est_M160K showed enhanced T_1/2 of 36.8 h at 70 °C in comparison to free enzyme. lx-Est_M160K could degrade various pyrethroid pesticides. After 40 min reaction with 50 U of the lx-Est_M160K, the malathion removal was 95.8% with a malathion concentration of 20 mg/L. When 2.5 g lx-Est_M160K was added to the 10 mL column reactor with the concentration of bifenthrin was 500 mg/L and the transfer rate of the pump was 0.7 mL/min, the degradation rate of lx-Est_M160K to bifenthrin was 90.4%. lx-Est_M160K exhibited high operational stability and maintained 72% initial activity after ten batches of continuous reaction for bifenthrin pesticide biodegradation. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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Review

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31 pages, 2478 KiB

Open AccessReview

Overview of Recent Advances in Immobilisation Techniques for Phenol Oxidases in Solution

by Thandanani Ndlovu, Sidy Ba and Soraya P Malinga

Catalysts 2020, 10(5), 467; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10050467 - 25 Apr 2020

Cited by 6 | Viewed by 3836

Abstract

Over the past two decades, phenol oxidases, particularly laccases and tyrosinases, have been extensively used for the removal of numerous pollutants in wastewaters due to their broad substrate specificity and their ability to use readily accessible molecular oxygen as the essential cofactor. As for other enzymes, immobilisation of laccases and tyrosinases has been shown to improve the performance and efficiency of the biocatalysts in solution. Several reviews have addressed the enzyme immobilisation techniques and the application of phenol oxidases to decontaminate wastewaters. This paper offers an overview of the recent publications, mainly from 2012 onwards, on the various immobilisation techniques applied to laccases and tyrosinases to induce and/or increase the performance of the biocatalysts. In this paper, the emphasis is on the efficiencies achieved, in terms of structural modifications, stability and resistance to extreme conditions (pH, temperature, inhibitors, etc.), reactivity, reusability, and broad substrate specificity, particularly for application in bioremediation processes. The advantages and disadvantages of several enzyme immobilisation techniques are also discussed. The relevance and effectiveness of the immobilisation techniques with respect to wastewater decontamination are critically assessed. A perspective on the future directions for large-scale application of the phenol oxidases in immobilised forms is provided. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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Other

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10 pages, 843 KiB

Open AccessEditor’s ChoicePerspective

The Current State of Research on PET Hydrolyzing Enzymes Available for Biorecycling

by Fusako Kawai

Catalysts 2021, 11(2), 206; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11020206 - 03 Feb 2021

Cited by 54 | Viewed by 10477

Abstract

This short paper reviews two groups of enzymes designated as polyethylene terephthalate (PET) hydrolases: one consists of thermophilic cutinases from thermophilic microorganisms (actinomycetes and a fungus) and the other consists of mesophilic cutinases, the representative of which is IsPETase from a mesophilic bacterium. From the viewpoint that PET hydrolysis requires a high temperature close to the glass transition temperature (65–70 °C in water) of PET, mesophilic cutinases are not suitable for use in the enzymatic recycling of PET since their degradation level is one to three orders of magnitude lower than that of thermophilic cutinases. Many studies have attempted to increase the thermostability of IsPETase by introducing mutations, but even with these modifications, the mesophilic cutinase does not reach the same level of degradation as thermophilic cutinases. In addition, this kind of trial contradicts the claim that IsPETase works at ambient temperature. As plastic pollution is an urgent environmental issue, scientists must focus on feasible thermophilic enzymes for the enzymatic processing of disposed PET, rather than on mesophilic cutinases. Thermophilic and mesophilic cutinases must be evaluated precisely and comparatively, based on their features that enable them to hydrolyze PET, with the aim of enzymatic PET disposal. The level of thermophilic cutinases has already reached their optimal level in PET biorecycling. The optimal level may be reached through the processing of PET waste, by amorphization and micronization into readily hydrolysable forms and the improvement of PET hydrolases by engineering higher degradation ability and low-cost production. Here I summarize the critical points in the evaluation of PET hydrolases and discuss the biorecycling of PET. Full article

(This article belongs to the Special Issue Biocatalysts and Their Environmental Applications)

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