Simultaneous laccase production and transformation of bisphenol-A and triclosan using Trametes versicolor

Sustainable Approach for Degradation of Low-Density Polyethylene Plastic Waste Using Ligninolytic White Rot Fungus

Bisphenol A (BPA), an endocrine disruptor is used in manufacturing of polycarbonate plastics for food-drink packaging. In the present study, optimized set of conditions to degrade commercial grade BPA has been used and applied in degrading shredded leached low-density polyethylene (LDPE) residues and its leachate (198 µg/L BPA) using white rot fungus Hypocrea lixii. One-at-a-time method showed maximum BPA degradation of 98.73 ± 0.02% with 190.1 ± 0.2 U/L laccase and 1913.2 ± 0.3 U/L lignin peroxidase in glucose-yeast extract-malt extract-peptone (GYMP) medium supplemented with 5% sawdust, mediators-CuSO4 (0.2 mM), veratryl alcohol (0.1 mM) and Tween 80 (0.1 mM). Three sets were prepared by dissolving these optimized nutritional components in leachates-A (only leachate), B (leached LDPE residues in leachate) and C (leached LDPE residues, sawdust in leachate). All sets showed 100% degradation in 5 days. Cracks and holes in degraded LDPE pieces was confirmed by SEM analysis and changes in functional groups by FTIR. Toxicity assay of treated leachate on soil microfauna revealed the elimination of BPA as it supported sufficient microbial growth of soil bacteria. Thus, the present process provides a sustainable solution for the management of LDPE with the possibility of using treated leachate for irrigation.

Decisional tool development and application for techno-economic analysis of fungal laccase production

Textile and medical effluents causing bioaccumulation and biomagnification have been successfully biodegraded by fungal laccases. Here, a decision-making tool was developed and applied to evaluate 45 different laccase production strategies which determined the best potential source from a techno-economical perspective. Laccase production cost was calculated with a fixed output of 109 enzymatic units per batch (USD$per109U) and a sensitivity analysis was performed. Results indicate that optimization of enzymatic kinetics for each organism is essential to avoid exceeding the fermentation time point at which production titer reaches its peak and, therefore, higher production costs. Overall, the most cost-effective laccase-producing strategy was obtained when using Pseudolagarobasidium acaciicola with base production cost of USD $42.46 per 109 U. This works serves as platform for decision-making to find the optimal laccase production strategy based on techno-economic parameters.

Unveiling microbial degradation of triclosan: Degradation mechanism, pathways, and catalyzing clean energy

Emerging organic contaminants present in the environment can be biodegraded in anodic biofilms of microbial fuel cells (MFCs). However, there is a notable gap existing in deducing the degradation mechanism, intermediate products, and the microbial communities involved in degradation of broad-spectrum antibiotic such as triclosan (TCS). Herein, the possible degradation of TCS is explored using TCS acclimatized biofilms in MFCs. 95% of 5 mgL-1 TCS are been biodegraded within 84 h with a chemical oxygen demand (COD) reduction of 62% in an acclimatized-MFC (A-MFC). The degradation of TCS resulted in 8 intermediate products including 2,4 -dichlorophenol which gets further mineralized within the system. Concurrently, the 16S rRNA V3-V4 sequencing revealed that there is a large shift in microbial communities after TCS acclimatization and MFC operation. Moreover, 30 dominant bacterial species (relative intensity >1%) are identified in the biofilm in which Sulfuricurvum kujiense, Halomonas phosphatis, Proteiniphilum acetatigens, and Azoarcus indigens significantly contribute to dihydroxylation, ring cleavage and dechlorination of TCS. Additionally, the MFC was able to produce 818 ± 20 mV voltage output with a maximum power density of 766.44 mWm-2. The antibacterial activity tests revealed that the biotoxicity of TCS drastically reduced in the MFC effluent, signifying the non-toxic nature of the degraded products. Hence, this work provides a proof-of-concept strategy for sustainable mitigation of TCS in wastewaters with enhanced bioelectricity generation.

Purification, characterization of laccase from Pleurotus ostreatus HK35, and optimization for congo red biodecolorization using Box-Behnken design

This study is the first report on purification, characterization, and application of laccase derived from the white-rot fungus, Pleurotus ostreatus HK35 (Hungary strain), in Congo Red decolorization. The purification process involved ammonium sulfate precipitation, dialysis, anion exchange chromatography, and ultrafiltration, yielding a specific laccase activity of 15.26 U/mg and a 30.21% recovery rate. The purified enzyme, with a molecular weight of approximately 34 kilodaltons, displayed optimal activity at a temperature of 60 °C and pH 4.0 when using 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) as a substrate. The enzyme maintained over 82.02 ± 1.01% of its activity at temperatures up to 50 °C after 180 min but displayed less than 5% of its activity at 60 and 70 °C. Notably, the enzyme's activity was significantly enhanced by Pb(NO3)2, whereas β-mercaptoethanol completely inhibited the activity. Utilizing the Box-Behnken design, we optimized Congo Red decolorization efficiency to 91.05 ± 0.82% at 100 mg/L Congo Red, 1.5 mM mediator concentration, and 1.6 U/mL laccase activity. Analysis of Variance (ANOVA) suggested the model was significant, and all variables significantly influenced decolorization efficiency.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03926-7.

Optimizing the degradation of aflatoxin B1 in corn by Trametes versicolor and improving the nutritional composition of corn

BACKGROUND

Corn, being an important grain, is prone to contamination by aflatoxin B1 (AFB1 ), and AFB1 -contaminated corn severely endangers the health of humans and livestock. Trametes versicolor, a fungus that can grow in corn, possesses the ability to directly degrade AFB1 through its laccase. This study aimed to optimize the fermentation conditions for T. versicolor to degrade AFB1 in corn and investigate the effect of T. versicolor fermentation on the nutritional composition of corn. AFB1 -contaminated corn was used as the culture substrate for T. versicolor. A combination of single-factor experiments and response surface methodology was employed to identify the optimal conditions of AFB1 degradation.

RESULTS

The optimal conditions of AFB1 degradation were as follows: 9 days of fermentation, a fermentation temperature of 26.7 °C, a moisture content of 70.5% and an inoculation amount of 4.9 mL (containing 51.99 mg of T. versicolor mycelia). With the optimal conditions, the degradation rate of AFB1 in corn could reach 93.01%, and the dry basis content of protein and dietary fiber in the fermented corn was significantly increased. More importantly, the lysine content in the fermented corn was also significantly increased.

CONCLUSION

This is the first report that direct fermentation of AFB1 -contaminated corn by T. versicolor not only efficiently degrades AFB1 but also improves the nutritional composition of corn. These findings suggest that the fermentation of corn by T. versicolor is a promising, environmentally friendly and efficient approach to degrade AFB1 and improve the nutritional value of corn. © 2023 Society of Chemical Industry.

Multi-omics approaches for remediation of bisphenol A: Toxicity, risk analysis, road blocks and research perspectives

In this "plastic era" with the increased use of plastic in day today's life the accumulation of its degraded products like microplastics or plastic additives such as Bisphenol A(BPA) is also increasing. BPA is an endocrine-disrupting chemical used as a plasticizing agent in clear plastic, building materials, coatings, and epoxy resin. Several enzymes including laccases and lipases have been studied for the reduction of BPA toxicity. Over the decades of encountering these toxicants, microorganisms have evolved to degrade different classes of plastic additives. Since the degradation of BPA is a long process thus meta-omics approaches have been employed to identify the active microbiota and microbial dynamics involved in the mitigation of BPA. It is also necessary to investigate the impact of processing activities on transit of BPA in food items and to limit its entrance in food world. This review summarizes a comprehensive overview on BPA sources, toxicity, bio-based mitigation approaches along with a deeper understanding of multi-omics approaches for its reduction and risk analysis. Knowledge gaps and opportunities have been comprehensively compiled that would aid the state-of-the-art information in the available literature for the researchers to further address this issue.

The production of laccases by white-rot fungi under solid-state fermentation conditions

Laccases (E.C. 1.10.3.2) produced by white-rot fungi (WRF) can be widely used, but the high cost prevents their use in large-scale industrial processes. Finding a solution to the problem could involve laccase production by solid-state fermentation (SSF) simulating the natural growth conditions for WRF. SSF offers several advantages over conventional submerged fermentation (SmF), such as higher efficiency and productivity of the process and pollution reduction. The aim of this review is therefore to provide an overview of the current state of knowledge about the laccase production by WRF under SSF conditions. The focus is on variations in the up-stream process, fermentation and down-stream process and their impact on laccase activity. The variations of up-stream processing involve inoculum preparation, inoculation of the medium and formulation of the propagation and production media. According to the studies, the production process can be shortened to 5-7 days by the selection of a suitable combination of lignocellulosic material and laccase producer without the need for any additional components of the culture medium. Efficient laccase production was achieved by valorisation of wastes as agro-food, municipal wastes or waste generated from wood processing industries. This leads to a reduction of costs and an increase in competitiveness compared to other commonly used methods and/or procedures. There will be significant challenges and opportunities in the future, where SSF could become more efficient and bring the enzyme production to a higher level, especially in new biorefineries, bioreactors and biomolecular/genetic engineering.

Microbial capability for the degradation of chemical additives present in petroleum-based plastic products: A review on current status and perspectives

Plastic additives are present as pollutants in the environment because they are released from plastics and have been reported to be toxic to mammals. Due to this toxicity, it is crucial to develop ecofriendly tools to decontaminate the environment. Microorganisms are a promising alternative for efficient and effective plastic additive removal. This review describes the current knowledge and significant advances in the microbial degradation of plastic additives (i.e. plasticizers, flame retardants, stabilizers and antioxidants) and biotechnological research strategies that are being used to accelerate the biodegradation process of these additives. It is expected that further research supported by advances in genomics, proteomics, gene expression, enzyme immobilization, protein design, and nanotechnology can substantially increase our knowledge to enhance the enzymatic degradation efficiency, which will accelerate plastic additive degradation and establish successful and cost-effective bioremediation processes. Investigations should also address the identification of the enzymes involved in the degradation process and their catalytic mechanisms to achieve full metabolization of organopollutants (i.e. plastic additives) while avoiding harmful plastic additive biodegradation products. Microorganisms and their enzymes undoubtedly represent a potential resource for developing promising environmental biotechnologies, as they have the best systems for pollutant degradation, and their actions are essential for decontaminating the environment.

Effect of Pleurotus ostreatus and Trametes versicolor on triclosan biodegradation and activity of laccase and manganese peroxidase enzymes

INTRODUCTION

Triclosan (TCS) is an extensively used antibacterial agent which has been frequently detected in different environmental compartments. Because of TCS inhibition effect on vast majority of bacterial species, it is important to explore fungal species and their involved enzymes in TCS biodegradation. The aim of this study was to compare the potential of two white rot fungi Pleurotus ostreatus and Trametes versicolor for TCS biodegradation through the whole cell culture of fungi in an aqueous culture medium. Additionally, the changes in ligninolytic enzyme activities and possible correlations and contributions of degradative enzymes during TCS biodegradation process were monitored.

MATERIAL AND METHODS

This study was carried out using a factorial experiment with a completely randomized design in three replications. factorial design in The experimental factors included: two white rot fungi Pleurotus ostreatus and Trametes versicolor and uninoculated controls which were subjected to five levels of TCS concentrations (0, 5, 10, 20, 30 and 50 μg mL-1) to assess ligninolytic enzymatic activity during biodegradation of TCS. Samples were harvested periodically at three time intervals (4, 7 and 10 days). An AB SCIEX 3200 QTRAP LC-MS/MS system was used in order to analyze the biodegradation of TCS in liquid medium.

RESULTS

Results suggested that the two white rot fungi responded differently when exposed to the different concentrations of TCS. In general, P. ostreatus exhibited more potential and ligninolytic enzymatic activity compared to T. versicolor. LC-MS/MS analyses also showed that P. ostreatus degraded TCS with higher efficiency compared to T. versicolor. In addition, almost all P. ostreatus biodegradation activity was completed within the first day of sampling. Contrasting, less efficient degradation was observed by T. versicolor, reaching around 88% of TCS biodegradation at concentration of 20 μg mL-1after 10 days. At higher TCS concentrations (≥30 μg mL-1), the growth of T. versicolor severely inhibited and led to a drop in enzymatic activity and biodegradation. Furthermore, laccase and manganese peroxidase (MnP) were determined as more involved enzymes which significantly correlated to TCS biodegradation by T. versicolor and P. ostreatus, respectively.

CONCLUSION

P. ostreatus might be considered as efficient fungus in biodegradation of high amount of TCS in environmental matrices. The results of the present study might provide insights for future investigations on potential of fungi for applications in bioaugmentation-based strategies to remove TCS from wastewater and activated sludge.

Persistence, ecological risks, and oxidoreductases-assisted biocatalytic removal of triclosan from the aquatic environment

Triclosan (TCS) has been immensely employed in health care products and consumer items, as an active agent with fungicidal and bactericidal potentialities, such as soaps, sanitizers, tubes of toothpaste, deodorants, skin creams, and so on for over last five decades. The ultimate excretory route of TCS ends in our water matrices, thus has been frequently detected with ecological and human-health related matters and hazards. Bioactive residues of TCS reach into the key atmosphere compartment through numerous routes, such as (1) scarce or ineffective elimination or degradation throughout the treatment practices, (2) abandoned landfill leachates, (3) leakage from the discarded TCS-containing materials, and so on. Such persistence and occurrence of TCS or its degraded but bioactive residues have growing attentions. Its complete removal and/or effective prevention are still challenging tasks for safeguarding the environment. Owing to the highly effective catalytic and stability potential, enzyme-based bio-degradation approaches are considered an evocative substitute for TCS mitigation from environmental matrices. As compared to enzymes in their pristine form, immobilized enzymes, with unique catalytic, stability, selectivity, and reusability profile, are of supreme and strategic interest in environmental biotechnology. Herein, an effort has been made to signify the novel bio-catalytic and bio-degradation potentialities of various oxidoreductases, including laccases, and peroxidases including soybean peroxidase, versatile manganese peroxidase, and horseradish peroxidase with suitable examples. Following a brief introduction, the focus is given to the presence of TCS in the key atmosphere compartments. Potential sources, acquaintance, and hazardous influence of TCS are also discussed with recent and relevant examples. The second half shows the TCS removal/degradation potentialities of soluble enzyme-based catalytic systems and immobilized-enzyme-based catalytic systems. Finally, the concluding remarks, along with possible future directions are given in this significant research arena.

Organic Contaminant Biodegradation by Oxidoreductase Enzymes in Wastewater Treatment

Organic contaminants (OCs), such as pharmaceuticals, personal care products, flame retardants, and plasticisers, are societally ubiquitous, environmentally hazardous, and structurally diverse chemical compounds whose recalcitrance to conventional wastewater treatment necessitates the development of more effective remedial alternatives. The engineered application of ligninolytic oxidoreductase fungal enzymes, principally white-rot laccase, lignin peroxidase, and manganese peroxidase, has been identified as a particularly promising approach for OC remediation due to their strong oxidative power, broad substrate specificity, low energy consumption, environmental benignity, and cultivability from lignocellulosic waste. By applying an understanding of the mechanisms by which substrate properties influence enzyme activity, a set of semi-quantitative physicochemical criteria (redox potential, hydrophobicity, steric bulk and pKa) was formulated, against which the oxidoreductase degradation susceptibility of twenty-five representative OCs was assessed. Ionisable, compact, and electron donating group (EDG) rich pharmaceuticals and antibiotics were judged the most susceptible, whilst hydrophilic, bulky, and electron withdrawing group (EWG) rich polyhalogenated compounds were judged the least susceptible. OC susceptibility scores were in general agreement with the removal rates reported for experimental oxidoreductase treatments (R2 = 0.60). Based on this fundamental knowledge, and recent developments in enzyme immobilisation techniques, microbiological enzymic treatment strategies are proposed to formulate a new generation of biological wastewater treatment processes for the biodegradation of environmentally challenging OC compounds.

Fungal Laccase Production from Lignocellulosic Agricultural Wastes by Solid-State Fermentation: A Review

Laccases are copper-containing oxidase enzymes found in many fungi. They have received increasing research attention because of their broad substrate specificity and applicability in industrial processes, such as pulp delignification, textile bleaching, phenolic removal, and biosensors. In comparison with traditional submerged fermentation (SF), solid-state fermentation (SSF) is a simpler technique for laccase production and has many advantages, including higher productivity, efficiency, and enzyme stability as well as reduced production costs and environmental pollution. Here, we review recent advances in laccase production technology, with focus on the following areas: (i) Characteristics and advantages of lignocellulosic agricultural wastes used as SSF substrates of laccase production, including detailed suggestions for the selection of lignocellulosic agricultural wastes; (ii) Comparison of fungal laccase production from lignocellulosic substrates by either SSF or SF; (iii) Fungal performance and strain screening in laccase production from lignocellulosic agricultural wastes by SSF; (iv) Applications of laccase production under SSF; and (v) Suggestions and avenues for future studies of laccase production by fungal SSF with lignocellulosic materials and its applications.

Mitigation of bisphenol A using an array of laccase-based robust bio-catalytic cues - A review

Bisphenol A (BPA) is a known endocrine disruptor that poses concerning environmental and human-health related issues and ecological risks. It has been largely used as an intermediate in the manufacture of epoxy resins and polycarbonate plastics. Traces of BPA can reach into the environment through inadequate or inefficient removal during wastewater treatment, uncontrolled landfill leachates, and leaching out from the discarded BPA-based materials. Several physicochemical treatment methods including adsorption, Fenton, ozonation, electrochemical and photochemical degradation, and membrane filtration, have been applied for BPA elimination. However, these methods are not adequate for large-scale treatment due to some inherent limitations. Benefiting from high catalytic efficiency and specificity, enzyme-based bio-catalytic degradation strategies are considered quite meaningful alternative for efficient and effective BPA removal from different routes. Among various oxidoreductases, i.e., laccases exhibited a superior potential for the remediation of BPA-containing wastewater. Enzymatic oxidation of BPA can be boosted by using various natural or synthetic redox mediators. Immobilized enzymes can expand their applicability to continuous bioprocessing and facilitates process intensification. Therefore, optimized formulations of insolubilized biocatalysts are of strategic interest in the environmental biotechnology. In this review, recent research studies dealing with BPA removal by the laccase-catalyzed system are presented. At first, the presence of BPA in the ecosystem, sources, exposure, and its impact on the living organisms and human beings is summarized. Then, we highlighted the use of crude as well as immobilized laccases for the degradation of BPA. In addition to toxicity and estrogenicity removal studies, the unresolved challenges, concluding remarks, and possible future direction is proposed in this important research area. It is palpable from the literature reviewed that free as well as immobilized forms of laccases have displayed noteworthy potential for BPA removal from wastewater.

Enhancing laccase production by white-rot fungus trametes hirsuta SSM-3 in co-culture with yeast sporidiobolus pararoseus SSM-8

Due to wide application of laccase, many researchers have shown great interest in over production of white-rot fungi laccase by co-culture. In this study, a white-rot fungus Trametes hirsuta SSM-3, and a yeast Sporidiobolus pararoseus SSM-8 were isolated and identified from Mulberry fruit. The capacity of S. pararoseus to enhance laccase production was remarkable in T. hirsuta, yielding 31777 ± 742 U/L, about 9.9 times higher than the result from the monoculture. The stimulatory factor in the S. pararoseus cells might be temperature-sensitive. The laccase production was enhanced by oil-extract of S. pararoseus and β-carotene induction. The amylase activity was decreased rapidly when strain S. pararoseus SSM-8 was inoculated. The glucose deprivation was occurred both in the mono-culture and co-culture process, and S. pararoseus propagated slowly in co-culture all the time. Native-PAGE revealed an increase of laccase-1(lac-1) level and a laccase-3 (lac-3) in the co-culture. Therefore, it was concluded that competition for resources between the co-cultured microbes leaded to amylase decreasing and the enhanced production of laccase. This conclusion was helpful for the development of laccase fermentation industry because it provided an effective, simple and economic method to improve the yield of laccase.