Purification and characterization of two novel peroxidases from the dye-decolorizing fungus Bjerkandera adusta strain CX-9

Actinobacterial peroxidase-mediated biodeterioration of hazardous explosive, 2, 4, 6, trinitrophenol by in silico and in vitro approaches

Explosives are perilous and noxious to aquatic biota disrupting their endocrinal systems. Supplementarily, they exhibit carcinogenic, teratogenic and mutagenic effects on humans and animals. Henceforth, the current study has been targeted to biotransform the explosive, 2, 4, 6 trinitrophenol (TNP) by wetland peroxidase from Streptomyces coelicolor. A total peroxidase yield of 20,779 mg/l with 51.6 folds of purification was observed. In silico molecular docking cum in vitro appraisals were accomplished to assess binding energy and interacting binding site residues of peroxidase and TNP complex. TNP required a minimal binding energy of-6.91 kJ/mol and was subjected to biodeterioration (89.73%) by peroxidase in purified form, with 45 kDa and a similarity score of 34 by MASCOT protein analysis. Moreover, the peroxidase activity was confirmed with Zymogram analysis. Characterization of peroxidase revealed that optimum values of pH and temperature as 6 and 40 °C, respectively, with their corresponding stability varying from 3.5 to 7. Interestingly, the kinetic parameters such as Km and Vmax on 2,2'-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and H2O2 were 19.27 µm and 0.41 µm/min; 21.4 µm and 0.1 µm/min, respectively. Among the diverse substrates, chemicals and trace elements, ABTS (40 mM), citric acid (5 mM) and Fe2+ (5 mM) displayed the highest peroxidase activity. Computational docking and in vitro results were corroborative and UV-Vis spectroscopy, HPLC, FTIR and GC-MS indicated the presence of simple metabolites of TNP such as nitrophenols and benzoquinone, showcasing the efficacy of S. coelicolor peroxidase to biotransform TNP. Henceforth, the current study offers a promising channel for biological treatment of explosive munitions, establishing a sustainable green earth.

Advances from conventional to biochar enhanced biotreatment of dyeing wastewater: A critical review

DW (Dyeing wastewater) contains a large amount of dye organic compounds. A considerable proportion of dye itself or its intermediate products generated during wastewater treatment process exhibits CMR (Carcinogenic/Mutagenic/Toxic to Reproduction) toxicity. Compared with physicochemical methods, biological treatment is advantageous in terms of operating costs and greenhouse gas emissions, and has become the indispensable mainstream technology for DW treatment. This article reviews the adsorption and degradation mechanisms of dye organic compounds in wastewater and analyzed different biological processes, ranging from traditional methods to processes enhanced by biochar (BC). For traditional biological processes, microbial characteristics and communities were discussed, as well as the removal efficiency of different bioreactors. BC has adsorption and redox electron mediated effects, and coupling with biological treatment can further enhance the process of biosorption and degradation. Although BC coupled biological treatment shows promising dye removal, further research is still needed to optimize the treatment process, especially in terms of technical and economic competitiveness.

Deciphering ligninolytic enzymes in the secretome of Pycnoporus sp. and their potential in degradation of 2-chlorophenol

Chlorophenols and their derivatives are persistent environmental pollutants, posing a threat to terrestrial and aquatic life. The biological approach for eliminating toxic contaminants is an effective, sustainable, and environmental friendly method. In this study, the crude enzymes present in the secretome of white-rot fungus (Pycnoporus sp.) were explored for the degradation of 2-chlorophenol. The activity of ligninolytic enzymes in the secretome was analyzed and characterized for their kinetics and thermodynamic properties. Laccase and manganese peroxidase were prevalent ligninolytic enzymes and exhibited temperature stability in the range of 50-65 °C and pH 4-5, respectively. The kinetic parameters Michaelis constant (Km) and turnover number (Kcat) for Lac were 42.54 μM and 45 s-1 for 2,2'-azino-bis (3-ethylben- zothiazoline-6-sulfonic acid), and 93.56 μM and 48 s-1 towards 2,6-dimethoxyphenol whereas Km and Kcat for MnP were 2039 μM and 294 s-1 for guaiacol as substrate. Treatment with the crude enzymes laccase and manganese peroxidase results in the reduction of 2-chlorophenol concentration, confirmed by UV-visible absorption spectra and high-performance liquid chromatography analysis. The detoxification of 2-chlorophenol into less toxic forms was confirmed by the plate toxicity assay. This study demonstrated that crude enzymes produced by Pycnoporus sp. could potentially minimize the toxicity of phenolic compounds in a sustainable way.

Manganese peroxidases as robust biocatalytic tool - An overview of sources, immobilization, and biotechnological applications

With robust catalytic features, manganese peroxidases (MnPs) from various sources, including fungi and bacteria, have gained much consideration in many biotechnological applications with particular emphasis on environmental remediation. MnP is a heme-containing enzyme that belongs to the oxidoreductases that can catalyze the degradation of various organic pollutants, such as chlorophenols, nitroaromatic compounds, industrial dyes, and polycyclic aromatic hydrocarbons. To spotlight the MnP as biocatalytic tool, an effort has been put forward to cover the four major compartments. For instance, following a brief introduction, first, various microbial sources of MnP are discussed with examples. Second, structural attributes and biocatalytic features of MnP are given with examples. Third, different MnP immobilization strategies, including adsorption, covalent linking, entrapment, and cross-linking, are discussed with a significant motive to strengthen the enzyme's stability against diverse deactivation agents by restricting the conformational mobility of molecules. Compared to free counterparts, immobilized MnP fractions perform well in hostile environments. Finally, various biotechnological applications, such as fuel ethanol production, de-lignification, textile industry, pulp and paper industry, degradation of phenolic and non-phenolic compounds, and pharmaceutical and pesticide degradation, are briefly discussed.

Peroxidases-based enticing biotechnological platforms for biodegradation and biotransformation of emerging contaminants

Rampant industrial boom, urbanization, and exponential population growth resulted in widespread environmental pollution, with water being one of the leading affected resources. All kinds of pollutants, including phenols, industrial dyes, antibiotics, pharmaceutically active residues, and persistent/volatile organic compounds, have a paramount effect, either directly or indirectly, on human health and aquatic entities. Strategies for affordable and efficient decontamination of these emerging pollutants have become the prime focus of academic researchers, industry, and government to constitute a sustainable human society. Classical treatment techniques for environmental contaminants are associated with several limitations, such as inefficiency, complex pretreatments, overall high process cost, high sludge generation, and highly toxic side-products formation. Enzymatic remediation is considered a green and ecologically friendlier method that holds considerable potential to mitigate any kinds of contaminating agents. Exploiting the potential of various peroxidases for pollution abatement is an emerging research area and has considerable advantages, such as efficiency and ease of handling, over other methods. This work is designed to provide recent progress in deploying peroxidases as green and versatile biocatalytic tools for the degradation and transformation of a spectrum of potentially hazardous environmental pollutants to broaden their scope for biotechnological and environmental purposes. More studies are required to explicate the degradation mechanisms, assess the toxicology levels of bio-transformed metabolites, and standardize the treatment strategies for economic viability.

The First Comprehensive Biodiversity Study of Culturable Fungal Communities Inhabiting Cryoconite Holes in the Werenskiold Glacier on Spitsbergen (Svalbard Archipelago, Arctic)

Cryoconite holes on glacier surfaces are a source of cold-adapted microorganisms, but little is known about their fungal inhabitants. Here, we provide the first report of distinctive fungal communities in cryoconite holes in the Werenskiold Glacier on Spitsbergen (Svalbard Archipelago, Arctic). Due to a combination of two incubation temperatures (7 °C and 24 ± 0.5 °C) and two media during isolation (PDA, YPG), as well as classical and molecular identification approaches, we were able to identify 23 different fungi (21 species and 2 unassigned species). Most of the fungi cultured from cryoconite sediment were ascomycetous filamentous micromycetes. However, four representatives of macromycetes were also identified (Bjerkandera adusta, Holwaya mucida, Orbiliaceae sp., and Trametes versicolor). Some of the described fungi possess biotechnological potential (Aspergillus pseudoglaucus, A. sydowii, Penicillium expansum, P. velutinum, B. adusta, and T. versicolor), thus, we propose the Arctic region as a source of new strains for industrial applications. In addition, two phytopathogenic representatives were present (P. sumatraense, Botrytis cinerea), as well as one potentially harmful to humans (Cladosporium cladosporioides). To the best of our knowledge, we are the first to report the occurrence of A. pseudoglaucus, C. allicinum, C. ramotenellum, P. sumatraense, P. velutinum, P. cumulodentata, B. adusta, and T. versicolor in polar regions. In all likelihood, two unassigned fungus species (Orbiliaceae and Dothideomycetes spp.) might also be newly described in such environments. Additionally, due to experimenting with 10 sampling sites located at different latitudes, we were able to conclude that the number of fungal spores decreases as one moves down the glacier. Considering the prevalence and endangerment of glacial environments worldwide, such findings suggest their potential as reservoirs of fungal diversity, which should not be overlooked.

Enzymatic diversity of filamentous fungi isolated from forest soil incremented by sugar cane solid waste

Fungi are natural degraders of organic matter which can produce enzymes for many industrial and biotechnological applications. In this context, crude enzymatic extracts of fungal isolates were evaluated regarding their hydrolytic and ligninolytic abilities. The fungal strains were isolated from soil samples from Atlantic Rain Forest Park incremented with sugar cane biomass (filter cake), which allowed the selection of efficient lignocellulolytic enzymes. A total of 190 fungi were isolated and evaluated by endocellulase screenings. Thirteen fungi were selected about their hydrolytic and ligninolytic abilities. Among them, three isolates showed xylanolytic activity. Eleven of the isolates were selected by their cellulolytic abilities. Proteolytic enzymes were also detected for three fungi, allowing the classification as metalloprotease and serine protease. The isolates SPZPF3_47 (Mucor sp.), SPZPF1_129 (Byssochlamys nivea) and SPZPF1_141 (Paecilomyces saturatus) were selected for further investigation on their lignin peroxidase abilities. K_M, V_max and k_cat apparent for lignin peroxidases were also determined. The strain of Mucor sp. (SPZPF3_47) was highlighted since this fungal genus was not well described about its isolation in the adopted conditions in our study, and showing ligninolytic abilities.

Intragenomic Variability of ITS Sequences in Bjerkandera adusta

Bjerkandera adusta is a species of common white rot polyporoid fungi found worldwide. Despite playing an important role in deadwood decay, the species strains are used in bioremediation due to its ability to degrade polycyclic hydrocarbons and some of them are important etiological agents of chronic coughs and are associated with lung inflammations. In our experiments, diversity within the species was investigated using molecular approaches and we found that sequence diversity seen at ITS sequence level is not due to cryptic speciation but to intragenomic variability of ITS sequences in this species.

Microbial Degradation of Azo Dyes: Approaches and Prospects for a Hazard-Free Conversion by Microorganisms

Azo dyes have become a staple in various industries, as colors play an important role in consumer choices. However, these dyes pose various health and environmental risks. Although different wastewater treatments are available, the search for more eco-friendly options persists. Bioremediation utilizing microorganisms has been of great interest to researchers and industries, as the transition toward greener solutions has become more in demand through the years. This review tackles the health and environmental repercussions of azo dyes and its metabolites, available biological approaches to eliminate such dyes from the environment with a focus on the use of different microorganisms, enzymes that are involved in the degradation of azo dyes, and recent trends that could be applied for the treatment of azo dyes.

Selective Homologous Expression of Recombinant Manganese Peroxidase Isozyme of Salt-Tolerant White-Rot Fungus Phlebia sp. MG-60, and Its Salt-Tolerance and Thermostability

Phlebia sp. MG-60 is the salt-tolerant, white-rot fungus which was isolated from a mangrove forest. This fungus expresses three kinds of manganese peroxidase (MGMnP) isozymes, MGMnP1, MGMnP2 and MGMnP3 in low nitrogen medium (LNM) or LNM containing NaCl. To date, there have been no reports on the biochemical salt-tolerance of these MnP isozymes due to the difficulty of purification. In present study, we established forced expression transformants of these three types of MnP isozymes. In addition, the fact that this fungus hardly produces native MnP in a high-nitrogen medium (HNM) was used to perform isozyme-selective expression and simple purification in HNM. The resulting MGMnPs showed high tolerance for NaCl compared with the MnP of Phanerochaete chrysosporium. It was worth noting that high concentration of NaCl (over 200 mM to 1200 mM) can enhance the activity of MGMnP1. Additionally, MGMnP1 showed relatively high thermo tolerance compared with other isozymes. MGMnPs may have evolved to adapt to chloride-rich environments, mangrove forest.

Microbial approaches for sustainable remediation of dye-contaminated wastewater: a review

The coloured effluents produced from different industries, such as textile, plastics, printing, cosmetics, leather and paper, are extremely toxic and a tremendous threat to the aquatic organisms and human beings. The removal of coloured dye pollutants from the aqueous environment is a great challenge and a pressing task. The growing demand for low-cost and efficient treatment approaches has given rise to alternative and eco-friendly methods, such as biodegradation and microbial remediation. This work summarizes the overview and current research on the remediation of dye pollutants from the aqueous environment by microbial bio-sorbents, such as bacteria, fungi, algae, and yeast. In addition, dye degradation capabilities of microbial enzymes have been highlighted and discussed. Further, the influence of various experimental parameters, such as temperature, pH, and concentrations of nutrients, and dye, has been summarized. The proposed mechanism for dye removal by microorganisms is also discussed. The object of this review is to provide a state-of-the-art of microbial remediation technologies in eliminating dye pollutants from water resources.

Biodelignification of lignocellulose using ligninolytic enzymes from white-rot fungi

Lignocellulose is the most abundant biomass available on earth, including wood and agricultural wastes such as rice straw, corn cobs, and oil palm empty bunches. The biopolymer content in lignocellulose has a great potential as feedstock for producing industrial raw materials such as glucose, sorbitol, xylose, xylitol, and other pharmaceutical excipients. Currently, scientists and governments agree that the enzymatic delignification method is an environmentally friendly green method to be applied. This review attempts to explain the proper preparation of the enzymes laccase, lignin peroxidase, and manganese peroxidase, as well as the important factors influencing their activity. The recent applications of the enzymes for detoxification of hazardous substances, proper enzyme immobilization technique, and future prospect combination with DESs extraction of lignin are also discussed.

Fungal lignocellulolytic enzymes and lignocellulose: A critical review on their contribution to multiproduct biorefinery and global biofuel research

The continuous increase in the global energy demand has diminished fossil fuel reserves and elevated the risk of environmental deterioration and human health. Biorefinery processes involved in producing bio-based energy-enriched chemicals have paved way to meet the energy demands. Compared to the thermochemical processes, fungal system biorefinery processes seems to be a promising approach for lignocellulose conversion. It also offers an eco-friendly and energy-efficient route for biofuel generation. Essentially, ligninolytic white-rot fungi and their enzyme arsenals degrade the plant biomass into structural constituents with minimal by-products generation. Hemi- or cellulolytic enzymes from certain soft and brown-rot fungi are always favoured to hydrolyze complex polysaccharides into fermentable sugars and other value-added products. However, the cost of saccharifying enzymes remains the major limitation, which hinders their application in lignocellulosic biorefinery. In the past, research has been focused on the role of lignocellulolytic fungi in biofuel production; however, a cumulative study comprising the contribution of the lignocellulolytic enzymes in biorefinery technologies is still lagging. Therefore, the overarching goal of this review article is to discuss the major contribution of lignocellulolytic fungi and their enzyme arsenal in global biofuel research and multiproduct biorefinery.

A novel Bacillus ligniniphilus catechol 2,3-dioxygenase shows unique substrate preference and metal requirement

Identification of novel enzymes from lignin degrading microorganisms will help to develop biotechnologies for biomass valorization and aromatic hydrocarbons degradation. Bacillus ligniniphilus L1 grows with alkaline lignin as the single carbon source and is a great candidate for ligninolytic enzyme identification. The first dioxygenase from strain L1 was heterologously expressed, purified, and characterized with an optimal temperature and pH of 32.5 °C and 7.4, respectively. It showed the highest activity with 3-ethylcatechol and significant activities with other substrates in the decreasing order of 3-ethylcatechol > 3-methylcatechol > 3-isopropyl catechol > 2, 3-dihydroxybiphenyl > 4-methylcatechol > catechol. It did not show activities against other tested substrates with similar structures. Most reported catechol 2,3-dioxygenases (C23Os) are Fe²⁺-dependent whereas Bacillus ligniniphilus catechol 2,3-dioxygenase (BLC23O) is more Mn²⁺- dependent. At 1 mM, Mn²⁺ led to 230-fold activity increase and Fe²⁺ led to 22-fold increase. Sequence comparison and phylogenetic analyses suggested that BL23O is different from other Mn-dependent enzymes and uniquely grouped with an uncharacterized vicinal oxygen chelate (VOC) family protein from Paenibacillus apiaries. Gel filtration analysis showed that BLC23O is a monomer under native condition. This is the first report of a C23O from Bacillus ligniniphilus L1 with unique substrate preference, metal-dependency, and monomeric structure.

Investigation of promoter regions, motifs, and CpG islands in the regulation of gene expression in Trametes hirsuta strain 072

Background

In silico analysis of transcription start sites, promoter regions, transcription factors and their binding sites, and CpG islands for the Trametes hirsuta strain 072 genome were performed to understand the regulation mechanisms of gene expression and its genetic variations in the genomes. Therefore, a computational survey was carried out for the Trametes hirsuta strain 072 genome with the open reading frames from the National Center for Biotechnology Information database. Seventeen functional sequences were used to analyze promoter regions and their regulatory elements.

Result

The present study revealed that 94% of Trametes hirsuta strain 072 genes contained more than two TSSs. Among these identified TSSs, a TSS with the highest predictive score was considered to determine a promoter region of the genes. Moreover, a total of five common candidate motifs such as MotI, MotII, MotIII, MotIV, and MotV were identified. Among these motifs, motif IV was investigated as the common promoter motif for 41.17% of genes that serve as binding sites for transcription factors (TFs) involved in the expression regulation of Trametes hirsuta strain 072 genes. Motif IV was also compared to registered motifs in publically available databases to see if they are similar to known regulatory motifs for TF using TOMTOM web server. Hence, it was revealed that MotIV might serve as the binding site mainly for the leucine zipper TF gene family to regulate a gene expression of Trametes hirsuta strain 072. Regarding CpG island determination, it was concluded that there is no CpG island in both promoter and gene body regions of the Trametes hirsuta strain 072 genome.

Conclusions

This study provides a better insight into further molecular characterization which aimed to efficiently exploit a white rot fungus, Trametes hirsuta strain 072, for several biotechnological applications aimed to revitalize a severely contaminated environment.

Enzyme-assisted bioremediation approach for synthetic dyes and polycyclic aromatic hydrocarbons degradation

Environmental protection from emerging pollutants has become a significant challenge for mankind as an increasing number of contaminants, including synthetic dyes and polycyclic aromatic hydrocarbons (PAHs), represent a serious risk to ecological and environmental balance. Most synthetic dyes have complex aromatic structures and are resistant to degrade by classical approaches, such as physical and chemical processes, including adsorption, chemical coagulation, flocculation, ion exchange, membrane separation, froth flotation, and reverse osmosis. Enzymes-assisted catalytic transformation of pollutants has become a potential alternative to classical methods because of their ability to react with complex compounds, a quick degradation rate, and producing less harmful by-products. Plant peroxidases, and microbial laccase and lignin-degrading peroxidases (manganese and lignin peroxidase) have gained significant attention for treating aromatic waste due to their capability of oxidizing and detoxifying a wide range of recalcitrant xenobiotics, including PAHs and synthetic dyes. Peroxidases being efficient biocatalysts detoxify an array of toxic compounds by simple free-radical mechanism resulting in the formation of oxidized and depolymerized products of significantly reduced toxicity. Moreover, it is an ecofriendly and economically favorable approach towards the biodegradation of recalcitrant and toxic industrial waste. Among microbial and plant peroxidases, bacterial enzymes have broad substrate specificity and can transform a wide range of recalcitrant substrates. Ligninolytic enzymes oxidize the aromatic ring into quinones and acids by producing free hydroxyl radicals instead of dihydrodiols and mineralize aromatic hydrocarbon in combination with cytochrome P450, monooxygenases, and epoxide hydrolases. In the review, an attempt has been made to provide detailed knowledge about the availability of inexpensive peroxidases sources, their mechanism of action, and degradation potential. The present review summarizes the exploitation of peroxidases from plants, bacteria, and fungus (manganese peroxidase, lignin peroxidase, and laccases) for detoxification and degradation of textile dyes as well as PAHs. Conclusively, peroxidases have great potential to react with almost all classes of synthetic dyes and most PAHs due to broad substrate specificity and transformed them into less harmful metabolites.

Functional Characterization of Melanin Decolorizing Extracellular Peroxidase of Bjerkandera adusta

Melanin pigmentation in the human skin results from complicated cellular mechanisms that remain to be entirely understood. Uneven melanin pigmentation has been counteracted by inhibiting synthesis or transfer of melanin in the skin. Recently, an enzymatic approach has been proposed, wherein the melanin in the skin is decolorized using lignin peroxidase. However, not many enzymes are available for decolorizing melanin; the most studied one is lignin peroxidase derived from a lignin degrading fungus, Phanerochaete chrysosporium. Our current study reveals that versatile peroxidase from Bjerkandera adusta can decolorize synthetic melanin. Melanin decolorization was found to be dependent on veratryl alcohol and hydrogen peroxide, but not on Mn²⁺. The degree of decolorization reached over 40% in 10 min at 37 °C and a pH of 4.5. Optimized storage conditions were slightly different from those for the reaction; crude enzyme preparation was the most stable at 25 °C at pH 5.5. Since the enzyme rapidly lost its activity at 50 °C, stabilizers were screened. As a result, glycerol, a major component in several cosmetic formulations, was found to be a promising excipient. Our results suggest that B. adusta versatile peroxidase can be considered for future cosmetic applications aimed at melanin decolorization.

Textile Dye Biodecolorization by Manganese Peroxidase: A Review

Wastewater emissions from textile factories cause serious environmental problems. Manganese peroxidase (MnP) is an oxidoreductase with ligninolytic activity and is a promising biocatalyst for the biodegradation of hazardous environmental contaminants, and especially for dye wastewater decolorization. This article first summarizes the origin, crystal structure, and catalytic cycle of MnP, and then reviews the recent literature on its application to dye wastewater decolorization. In addition, the application of new technologies such as enzyme immobilization and genetic engineering that could improve the stability, durability, adaptability, and operating costs of the enzyme are highlighted. Finally, we discuss and propose future strategies to improve the performance of MnP-assisted dye decolorization in industrial applications.

A comprehensive insight into the application of white rot fungi and their lignocellulolytic enzymes in the removal of organic pollutants

Environmental problems resultant from organic pollutants are a major current challenge for modern societies. White rot fungi (WRF) are well known for their extensive organic compound degradation abilities. The unique oxidative and extracellular ligninolytic systems of WRF that exhibit low substrate specificity, enable them to display a considerable ability to transform or degrade different environmental contaminants. In recent decades, WRF and their ligninolytic enzymes have been widely applied in the removal of polycyclic aromatic hydrocarbons (PAHs), pharmaceutically active compounds (PhACs), endocrine disruptor compounds (EDCs), pesticides, synthetic dyes, and other environmental pollutants, wherein promising results have been achieved. This review focuses on advances in WRF-based bioremediation of organic pollutants over the last 10 years. We comprehensively document the application of WRF and their lignocellulolytic enzymes for removing organic pollutants. Moreover, potential problems and intriguing observations that are worthy of additional research attention are highlighted. Lastly, we discuss trends in WRF-remediation system development and avenues that should be considered to advance research in the field.

Bio-Delignification of Green Waste (GW) in Co-Digestion with the Organic Fraction of Municipal Solid Waste (OFMSW) to Enhance Biogas Production

The organic fraction of municipal solid waste (OFMSW) is recognized as a suitable substrate for the anaerobic digestion (AD) process and is currently considered a mature technology. A promising strategy to enhance biogas yield and productivity is the co-digestion of OFMSW with other organic biomass, such as green waste (GW), a mixture of leaves, grass, and woody materials originated from private yards and public greenspace management. The main limitation to the use of GW for biogas production is the high percentage of the lignocellulosic fraction, which makes necessary a pretreatment of delignification to dissolve the recalcitrant structure. In this study, a new strategy of sustainable bio-delignification using the white-rot fungi Bjerkandera adusta (BA) in comparison with other chemical pretreatments were investigated. Untreated and treated GW were, respectively, submitted to anaerobic co-digestion with OFMSW. AD processes were carried out in a lab-scale plant for 30 days in thermophilic conditions (55 °C). Biogas cumulative production was increased by about 100% in the case of treated GW compared with that of just OFMSW, from 145 to 289 Nm3 CH4/ton SV, and productivity almost doubled from 145 to 283 Nm3/ton FM * day. The measured average methane content values in the cumulative biogas were 55% from OFMSW and 54% from GW. Moreover, over 95% of the biogas was produced in 20 days, showing the potential opportunity to reduce the AD time.

3-Methyl-2-benzothiazolinone hydrazone and 3-dimethylamino benzoic acid as substrates for the development of polyphenoloxidase and phenoloxidase activity by zymograms

In the present study, a sequential staining process of polyphenoloxidase and phenoloxidase enzymes was designed by the zymography technique. As a first step, electrophoresis was carried out under native conditions, and later, first staining was carried out with a revealing solution of 3-methyl-2-benzothiazoline hydrazone (MBTH)-3-dimethylamino benzoic acid (DMAB) that allowed the visualization of polyphenoloxidase enzymes, and later and using the same gel, we proceeded to the differential staining of phenoloxidase, adding a solution of H2O2. The technique was standardized using commercial enzymes of laccase (T. versicolor) and horseradish. The technique was used to identify polyphenoloxidases (laccases) and phenoloxidases (lignin peroxidase) of crude extracts obtained from the growth of the basidiomycete Lentinus strigosus on Pinus radiata. The technique showed great sensitivity to detect the different enzymatic activities (1.56 Activity Unit/mL minimum) in the same gel without interference between the enzymes and the solutions used. On the other hand, the efficiency of the technique was compared with the substrates that are commonly used for the detection of this type of activities such as 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and guaiacol, observing greater sensitivity and minimal interference, so that the present method will allow in the same gel, and visualize polyphenoloxidase and phenoloxidase activities simultaneously facilitating expression studies.

Insights into the mechanism of cyanobacteria removal by the algicidal fungi Bjerkandera adusta and Trametes versicolor

Fungal mycelia can eliminate almost all cocultured cyanobacterial cells within a short time. However, molecular mechanisms of algicidal fungi are poorly understood. In this study, a time‐course transcriptomic analysis of algicidal fungus Bjerkandera adusta T1 was applied to investigate gene expression and regulation. A total of 132, 300, 422, and 823 differentially expressed genes (DEGs) were identified at 6, 12, 24, and 48 hr, respectively. Most DEGs exhibited high endopeptidase activity, cellulose catabolic process, and transmembrane transporter activity by using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Many decomposition genes encoding endopeptidases were induced a little later in B. adusta T1 when compared with previously investigated algicidal fungus Trametes versicolor F21a. Besides, the accumulated expression of Polysaccharide lyases8 (PL8) gene with peptidoglycan and alginate decomposition abilities was greatly delayed in B. adusta T1 relative to T. versicolor F21a. It was implied that endopeptidases and enzymes of PL8 might be responsible for the strong algicidal ability of B. adusta T1 as well as T. versicolor F21a.

Oxidative enzymes from newly local strain Aspergillus iizukae EAN605 using pumpkin peels as a production substrate: Optimized production, characterization, application and techno-economic analysis

The present study deals with optimizing, producing, characterizing, application and techno- economic analysis of oxidative enzymes [Laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP)] from Aspergillus iizukae EAN605 in submerged fermentation process using pumpkin peels as a production substrate. The best operating parameters for producing Lac, MnP and LiP (6.15, 2.58 and 127.99 U mg^-1 respectively) were recorded with 20 g 100 mL^-1 of substrate, 4.6 mL 100 mL^-1 of inoculum size at pH 5.5 after 10 days. The crude enzyme exhibited high stability at pH (3-9) and temperatures (20-60 °C). K_m (Michaelis-Menten) of Lac, MnP and LiP crude enzyme was 2.25, 1.79 and 0.72 mM respectively. The decolourization of Remazol Brilliant Blue R by the crude enzyme was 84.84 %. The techno-economic analysis was assessed for a production unit with an annual operating time for enzymatic production and application is 7920 h/year and 100 m³ of the capacity. The process would produce 27,000 cm³ of crude enzyme with a price of USD 0.107 per cm³ compared to USD 1 per cm³ of the current commercial enzyme. The findings indicated that pumpkin peels have potential as a production substrate for oxidative enzymes from A. iizukae EAN605 and is economically feasible.

Two Manganese Peroxidases and a Laccase of Trametes polyzona KU-RNW027 with Novel Properties for Dye and Pharmaceutical Product Degradation in Redox Mediator-Free System

Two manganese peroxidases (MnPs), MnP1 and MnP2, and a laccase, Lac1, were purified from Trametes polyzona KU-RNW027. Both MnPs showed high stability in organic solvents which triggered their activities. Metal ions activated both MnPs at certain concentrations. The two MnPs and Lac1, played important roles in dye degradation and pharmaceutical products deactivation in a redox mediator-free system. They completely degraded Remazol brilliant blue (25 mg/L) in 10-30 min and showed high degradation activities to Remazol navy blue and Remazol brilliant yellow, while Lac1 could remove 75% of Remazol red. These three purified enzymes effectively deactivated tetracycline, doxycycline, amoxicillin, and ciprofloxacin. Optimal reaction conditions were 50 °C and pH 4.5. The two MnPs were activated by organic solvents and metal ions, indicating the efficacy of using T. polyzona KU-RNW027 for bioremediation of aromatic compounds in environments polluted with organic solvents and metal ions with no need for redox mediator supplements.

Effect of lignocellulosic enzymes on the treatment of mature landfill leachate

The inherent necessity to remediate refractory contaminants from the toxic problematic wastewater like mature landfill leachate (MLL) has become a global challenge. This study investigated the effect of a potentially sustainable technological approach, i.e. lignocellulosic enzymatic activities (lignin-peroxidase, manganese-peroxidase and laccase), produced from six selected fungi on the removal efficiency of chemical oxygen demand (COD) and soluble COD (sCOD) from the MLL. The COD/sCOD removal percentage was significantly increased with higher enzymatic activities. Tyromyces chioneus was revealed to be the first ever fungi that produced significant amount of all three enzymes. Penicillium sp. and Tyromyces chioneus were the most effective strains, which removed 66% and 59% of COD, and 64% and 57% of sCOD, respectively. The maximum lignin-peroxidase, manganese-peroxidase and laccase enzymatic activities were 19.3 and 26.9 U/L by Tyromyces chioneus, and 249.8 U/L by Penicillium sp, respectively. It was concluded that lignocellulosic biomass could be a sustainable and advanced biological treatment option to remove refractory components from MLL.

Physical and enzymatic properties of a new manganese peroxidase from the white-rot fungus Trametes pubescens strain i8 for lignin biodegradation and textile-dyes biodecolorization

A new manganese peroxidase-producing white-rot basidiomycete fungus was isolated from symptomatic wood of the camphor trees Cinnamomum camphora (L.) at the Hamma Botanical Garden (Algeria) and identified as Trametes pubescens strain i8. The enzyme was purified (MnP TP55) to apparent electrophoretic homogeneity and biochemically characterized. The specific activity and Reinheitzahl value of the purified enzyme were 221 U/mg and 2.25, respectively. MALDI-TOF/MS analysis revealed that the purified enzyme was a monomer with a molecular mass of 55.2 kDa. The NH₂-terminal sequence of the first 26 amino acid residues of MnP TP55 showed high similarity with those of white-rot fungal peroxidases. It revealed optimal activity at pH 5 and 40 °C. This peroxidase was completely inhibited by sodium azide and potassium cyanide, suggesting the presence of heme-components in its tertiary structure. Interestingly, MnP TP55 showed higher catalytic efficiency, organic solvent-tolerance, dye-decolorization ability, and detergent-compatibility than that of horseradish peroxidase (HRP) from roots of Armoracia rustanica, manganese peroxidase from Bjerkandera adusta strain CX-9 (MnP BA30), and manganese peroxidase from Phanerochaete chrysosporium (MnP PC). Overall, the findings provide strong support for the potential candidacy of MnP TP55 for environmental applications, mainly the development of enzyme-based technologies for lignin biodegradation, textile-dyes biodecolorization, and detergent formulations.