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In recent years, many research on the quantity of lignocellulosic waste have been developed. The production, partial purification, and characterisation of ligninolytic enzymes from various fungi are described in this work. On the 21st day of incubation in Potato Dextrose (PD) broth, Hypsizygus ulmarius developed the most laccase (14.83 × 10−6 IU/ml) and manganese peroxidase (24.11 × 10−6 IU/ml), while Pleurotus florida produced the most lignin peroxidase (19.56 × −6 IU/ml). Laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP), all generated by selected basidiomycetes mushroom fungi, were largely isolated using ammonium sulphate precipitation followed by dialysis. Laccase, lignin peroxidase, and manganese peroxidase purification findings indicated 1.83, 2.13, and 1.77 fold purity enhancements, respectively. Specific activity of purified laccase enzyme preparations ranged from 305.80 to 376.85 IU/mg, purified lignin peroxidase from 258.51 to 336.95 IU/mg, and purified manganese peroxidase from 253.45 to 529.34 IU/mg. H. ulmarius laccase (376.85 IU/mg) with 1.83 fold purification had the highest specific activity of all the ligninolytic enzymes studied, followed by 2.13 fold purification in lignin peroxidase (350.57 IU/mg) and manganese peroxidase (529.34 IU/mg) with 1.77-fold purification. Three notable bands with molecular weights ranging from 43 to 68 kDa and a single prominent band with a molecular weight of 97.4 kDa were identified on a Native PAGE gel from mycelial proteins of selected mushroom fungus. The SDS PAGE profiles of the mycelial proteins from the selected mushroom fungus were similar to the native PAGE. All three partially purified ligninolytic isozymes display three bands in native gel electrophoresis, with only one prominent band in enzyme activity staining. The 43 kDa, 55 kDa, and 68 kDa protein bands correspond to laccase, lignin peroxidase, and manganese peroxidase, respectively.

White-rot fungi are thought to hold promise for development of a delignification pretreatment process for wood biorefinery that is less energy-consuming than current processes. However, the reaction must take place over weeks and consumes non-neglectable amounts of saccharides. To establish a biological process for wood biorefinery would first require establishment of an enzymatic approach to delignification. Such an approach has the potential to lower costs and reduce saccharide loss. Here, we attempted enzymatic delignification reactions using manganese peroxidases (MnP), a lignin-degrading enzyme, under several reaction conditions. The delignification rate from beech wood meal (particle size45 μm) of up to 11.0% in 48 h was reached in a MnP reaction supplemented with multiple co-oxidants, glucose, glucose oxidase (GOD) and commercial cellulase. An additional 48-h reaction using fresh MnP/co-oxidants increased the delignification rate to 14.2%. Simultaneous enzymatic delignification and saccharification, which occurs without a need for glucose supplementation, successfully improved the glucose yield to 160% of the reaction without MnP. Development of a more accurate imitation of the mechanisms of delignification that occurs in white-rot fungi has the potential to improve the monosaccharide yield resulting from simultaneous delignification and saccharification.

By using the indigenous micro-organisms of the polluted environment to be treated, bioremediation can be a successful strategy. PCR and RT-PCR molecular techniques were applied to examine the evolution of fungal isolates through putative genes f ligninolytic enzymes like lignin peroxidase (LiP), laccase (LaC), manganese peroxidase (MnP), and cellulase (Cx) as a response to polluting of the environment by hydrocarbons. In this study, isolation of rhizospheric fungal isolates, molecular identification, crude oil tolerance, and enzyme excretions were demonstrated. From the date palm rhizosphere, 3 fungal isolates were isolated and characterized morphologically and molecularly by ITS ribosomal RNA (rRNA) sequencing. The isolates were identified as Aspergillus flavus AF15, Trichoderma harzianum TH07, and Fusarium solani FS12 through using the BLAST tool in NCBI. All fungal isolates showed high tolerance to crude oil and survived with various responses at the highest concentration (20%). Aspergillus flavus AF15 and Trichoderma harzianum TH07 demonstrated promising oil-degrading tolerance ability based on the dose inhibition response percentage (DIRP) of the fungal isolates. A. flavus had a powerful capacity to production Cx, LaC, LiP and MnP with a range from 83.7 to 96.3 mL. Molecularly, nine genes of the ligninolytic enzymes, cbh (cbhI.1, cbhI.1, cbhII) lcc, lig (1, 2, 4 and 6) and mnp were tested for presence and expression (by PCR and RT-PCR, respectively). PCR showed that all isolates contained all the nine genes examined, regardless of capacity to enzymes production profiles, so the presence responses of nine genes did not correlate with enzymes-production ability. Gene expression analysis shows a more diverse pattern for tested isolates for example, Aspergillus flavus AF15 had over-expression of lig and mnp genes, Fusarium solani FS12 have a weak signal with lcc gene while, Trichoderma harzianum TH07 showed moderate expression of mnp and lcc genes. The power of the transcription of the gene leads to increased enzyme secretion by fungal isolates. Fungi are important microorganisms in the clean-up of petroleum pollution. They have bioremediation highly potency that is related to their diverse production of these catalytic enzymes.

Ligninolytic fungi contain a number of representative strains consisting of mainly white-rot fungi (WRF) that produce lignin-modifying enzymes (LME) such as laccases and manganese peroxidases. Lignin-modifying enzymes are multipurpose enzymes which have potential for application in various fields such as, for example, bioremediation and biomass conversion. Because of the non-specific nature of these enzymes, they are also capable of biodegradation and removal of xenobiotic pollutants. In this study we used a tiered screening process where we screened over 70 Vietnamese WRF fungal isolates for LME activity and subsequently for the ability to breakdown the dioxin TCDD. After the initial screening we selected four fungal strains, which belong to the order of Polyporales, which excreted high laccase enzyme levels. The most active fungus being isolate FMD21, a species of Rigidoporus, which was isolated from a forest in the South of Vietnam and which produced both laccase and manganese peroxidase. In the optimized PDSRb medium, FMD21 laccase levels reaced activities of 238800 U/L after 10 days while MnP activity showed the highest activity at day 4 of aproximately 40 U/L. 2,3,7,8-TCDD, which is the most toxic dioxin congener, is a persistent organic pollutant of which few organisms are known that break it down. After the final screening, FMD21 was the only fungus capable of degrading TCDD and was able to reach a breakdown percentage of 73% after 28 days culture with a start concentration of 0.5 pg TEQ/μL TCDD. Co-cultivation experiments of up to three fungi were performed to test for a synergistic breakdown effect of TCDD but such an effect was not observed. FMD21 is a fungus that shows a potential to be used as a bioremediation agent to clean up dioxin contamination in the environment.

Textile industry wastewater (TIWW) is a major source of environmental pollution causing serious threats to all life forms and thus, it must be adequately treated before its final discharge for the safety of environment and public health. In the present study, a potential bacterial strain (RKS9) was isolated from textile (wastewater & sludge) sample for the effective treatment of TIWW resulting in a significant reduction in pollution parameters such as ADMI color (93.87%), COD (77.35%), BOD (86.02%), TDS (66.75%), TOC (67.25%), TSS (60.34%), and phenol (68.55%) within 48 h. This bacterium also decolorized 99% of Congo red dye (100 mg L−1) within 12 h and removed 59.76%, 40.51%, 52.71% and 26.51% cadmium, chromium, lead and nickel, respectively from the TIWW. The activities of azoreductase, laccase, lignin peroxidase (LiP) and manganese peroxidase (MnP) was monitored and metabolites produced during the treatment of dye and TIWW were also analyzed by FT-IR and GC–MS. The phytotoxicity of the untreated and treated TIWW was assessed by seed germination and seedling growth parameters of Phaseolus mungo L. and results showed a significant reduction in the toxicity of the treated TIWW, suggesting that the isolated bacterium RKS9 has a remarkable potential to effectively decolorize/detoxify TIWW.

Fluorene, a low molecular weight polycyclic aromatic hydrocarbon (PAH), is of immense environmental interest because of its carcinogenicity, teratogenicity, mutagenicity, toxicity and persistence to microbial degradation. Existentially, there is paucity of information on PAH degradation by fungi isolated from marine environment. Therefore, this study investigated fluorene degradation efficiency of marine derived filamentous fungus, Mucor irregularis strain bpo1 (GenBank Accession Number: MK373020). Response Surface Methodology (RSM) using Box–Behnken Design (BBD) was successfully deployed in the optimization of process parameters (pH-7, temperature-32.5 °C, substrate concentration-100 mg L−1 and dry weight-2 g) resulting in 81.50% fluorene degradation on 5th day. The design and regression model were found to be statistically significant, adequate and appropriate with p < 0.0001, F value = 202.39, and predicted coefficient of determination (R2 = 0.9991). Optimization of the vital constituents of the mineral salt medium (MSM) used for the study using RSM-Central Composite Design (CCD) resulted in 79.80% fluorene degradation rate. Enhanced fluorene degradation efficiency (82.50%) was recorded when the optimized process variables were subjected to growth-linked validation experiments. The enzyme activities revealed 87%, 59% and 31% induction of laccase, manganese peroxidase and lignin peroxidase respectively. Four metabolites; 9H-fluoren-9-one, benzene-1,2-dicarboxylic acid, 2-hydroxybenzoic acid and phenol obtained after the experiment were characterized and confirmed with GC-MS analysis. The findings revealed the promising potentials of M. irregularis in PAH degradation and by extension green remediation technology. © 2020 The Authors

The rampant industrialization and unchecked growth of alcohol production facilities coupled with the lack of proper treatment facilities have proliferated the discharge of colored effluent enriched with high BOD, COD, TDS, and toxic androgenic and mutagenic compounds including endocrine-disrupting chemicals, phenolics, melanoidins, and heavy metals. Thus, the development of efficient and sustainable control measures against such pollution is imperative to safeguard ecosystems' natural resources and human health. A number of biological processes such as biodegradation and bioremediation, using fungi and their enzymes, have been reported having prospective application in color removal from distillery effluent. Biological methods present an incredible alternate for decolorization and degradation of distillery effluent due to their environmentally friendly and publicly acceptable treatment and cost-competitive alternative to chemical decomposition processes. Fungi, especially white-rot fungi can produce non-specific extracellular ligninolytic enzymes, i.e., lignin peroxidase, manganese peroxidase, and laccase. These enzymes are capable of degrading a wide spectrum of recalcitrant organic pollutants, such as melanoidins and phenol compounds. The chapter gives a clear explanation about the potential of fungi in degradation and decolorization of distillery effluent. In addition, the details mechanisms of fungal extracellular enzyme, especially ligninolytic enzyme system, in degradation and detoxification of melanoidins also discussed. Finally, the challenges and future prospects of distillery effluent treatment are also highlighted.

Six marine-derived fungi (Alternaria sp. D11, Alternaria sp. D21, Cadophora sp. D43, Cadophora luteo-olivacea D51, Phoma sp. K2BR, Phoma sp. K21) were isolated from the Cakalburnu Lagoon, Izmir Bay, Aegean Sea in Turkey. An effective method has been developed for marine-derived fungi isolation and laccase production of the fungi has been studied. This method consisted of immersing a sterile solid substrate containing lignin into the aquatic system under aseptic conditions and removing at the end of 10 days, isolation for laccase producing fungi of marine origin. The decolorization potential of the isolate Alternaria sp. D21 with the highest laccase activity was investigated for dyes containing azo, anthraquinone, triarylmethane and heterocyclic chemical classes. The decolorization rates were determined as 98% for Methyl orange, 93% for Acid green 3, 78% for Methylene blue, 71% for Remazol Brilliant Blue, 58% for Crystal violet, and 53% for Congo red after 144 h at 100 mg/L concentration of dyes. The ability of the marine-derived fungi to remove dyes of different chemical classes is also promising for waste containing mixtures of various pollutants. (C) 2021 Elsevier B.V. All rights reserved., Ege University Scientific Research Projects Coordination Unit [2017-FEN-037]; Ege University Scientific Research Projects Unit, Turkey, This work was supported by Ege University Scientific Research Projects Coordination Unit. Project Number: 2017-FEN-037. We would like to thank Ege University Scientific Research Projects Unit, Turkey for financial support.

In the present work, a strain of the basidiomycete fungus Trametes polyzona was used to decolorize the Amaranth dye. The decolorization was carried out in an Airlift reactor with three flow regimes: 1, 2, and 3 vvm. The results showed that the decolorization was a function of the flow regime. The decolorization times for the regimes of 1, 2, and 3 vvm were 30, 25, and 19 days, respectively. The COD (Chemical Oxygen Demand) decreased from 1600 to 72 mg COD/L. The enzymatic activity kinetics of laccase (Lcc), lignin peroxidase (LiP), and manganese peroxidase (MnP) were determined. In all the treatments, the enzyme LiP was expressed during the first 6 days, at which point 80% decolorization was observed, whereas Lcc and MnP enzymes were produced from day 6 until the end of the decolorization process. The effluent generated showed no inhibitory effects on the growth of the algae Nannochloropsis salina. T. polyzona showed great versatility in the decolorization of synthetic effluents containing the Amaranth dye, and the fungus was able to use this dye as its only carbon source starting at the beginning of the process. LiP was the enzyme that contributed the most to the decolorization process, and on average, 95% decreases in color and the COD were observed., Aeration, Amaranth dye, COD, Decolorization, Ligninolytic enzymes, Trametes polyzona

The pretreatment of carbonaceous material in double refractory gold ores (DRGO) is necessary to decrease preg-robbing of gold and maximize gold recovery. DRGO contains of carbonaceous matter and gold grains encapsulated in sulfide minerals, which typically results in very poor gold recovery. However, there is growing interest in DRGO because some estimates show that it makes up about a third of the total available gold for production by mining. This can be achieved by chemical and biological techniques, however, the chemical techniques like flotation, surface passivation and chemical oxidation have received more extensive study and either have to be retooled or modified to be applied to the carbonaceous matter in the DRGO. In comparison, the biological techniques are relatively unknown with significant gaps in the knowledge about the bio-treatment mechanism, byproducts and avenues for scaling up like bioreactor design. This study reviews the enzymatic pretreatment of DRGO to facilitate gold recovery and minimize reagent consumption. It focuses on the potential for application of oxidative enzymes like lignin peroxidase, manganese peroxidase and laccase to pretreat carbonaceous matter in DRGO with or without an additional step of sulfide oxidation and addresses characterization of byproducts of the enzymatic decomposition. Further, potential bioreactor configurations for the enzymatic decomposition without direct contact of ore with microorganisms are considered, both in terms of understanding the mechanisms within the pretreatment and in terms of application.

Untreated effluent containing toxic pollutants released from various industries represents an environmental threat and imbalances the ecological equilibrium. A large number of microbial enzymes have been involved in the biodegradation of various toxic organic pollutants. Phenols, polycyclic aromatic hydrocarbons, pesticides, dioxins and furans, polychlorinated biphenyls, industrial dyes, and lignin and its derivatives are among the most hazardous contaminants. Bioremediation is a cost-effective and eco-firendly process that is catalyzed by microbial enzymes. The ongoing research in this area would contribute to developing advanced technology to reduce the environmental pollution. Nowadays ligninolytic enzymes, that is, laccase, manganese peroxidase, lignin peroxidase, have gained more attention due to their various industrial applications. This chapter provides valuable information on the ligninolytic enzymes from various microorganisms involved in the biodegradation of recalcitrant organic pollutants, wastewater treatment, and also describes the structural, functional, and physicochemical properties of these enzymes.

The ligninolytic enzymes (laccase, manganese peroxidase, lignin peroxidase) have a wide range of applications, including in the industrial and environmental sectors. Lignin peroxidase (LiP; EC 1.11.1.14) is a heme-containing key enzyme of lignin degradation, and it is known as diaryl propane oxygenase. Being an oxidoreductase in chemical nature, LiP is an H2O2-dependent enzyme and catalyzes various phenolic and nonphenolic compounds. The diverse variety of microbes are known for LiP production in the environment. However, fungal-mediated ligninolytic enzymes have been studied extensively with its even greater advantages due to their thermostability, a wide range of pH values, fewer by-products, and high specificity. In the presenting chapter, we explore the ligninolytic enzymes, specially dedicated to lignin peroxidase. The broad and detailed information has dedicated to lignin peroxidases, like; the sources, production, mode of action, and various applications in industrial sectors. The potential use of this enzyme extends through many industries, including; pulp and paper, cosmetics, textile, bioremediation, energy, and cosmetics. Besides, this chapter also provides recent updates on lignin peroxidase production along with their current applications.

Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine), a derivative of s-triazine herbicide, is an antifouling compound used as an alternative to organotins. The compound is highly persistent and is known to be biodegraded only by the white rot fungus, Phanerochaete chrysosporium. We used partially purified manganese peroxidase (MnP) prepared from P. chrysosporium to evaluate its capacity to degrade Irgarol 1051. MnP degraded Irgarol 1051 to two major products, one identified as M1 (identical to GS26575, 2-methylthio-4-tert-butylamino-6-amino-s-triazine) and the other not identified but with same mass spectrum as M1 and a different ultraviolet spectrum. This report clearly demonstrates that this ligninolytic enzyme is involved in the degradation of Irgarol 1051.

The degradation of lindane was studied in liquid-agitated cultures using a commercial strain of the fungus Pleurotus ostreatus as the biodegrading organism. The biodegradation was accomplished with the action of extracellular oxidative enzymes, produced by the fungus to decompose woody substrates. Enzyme activities of manganese peroxidase and laccase were measured in a liquid mineral medium. An orthogonal Central Composite Design of experiments was used to construct second-order response surfaces with the fungus growth, final pH and the lindane biodegradation as optimization parameters. The initial lindane concentration, the nitrogen content, the incubation time and the temperature were used as design factors. Optimal conditions found for all these parameters will be used for the continuation of this project aiming at the bioremediation of contaminated sites with persistent organic pollutants such as lindane. Keywords: Bioremediation, Lindane, Fungi, Biodegradation, Ligninolytic enzymes, Response surface methodology, Central composite design

We investigated whether manganese peroxidase (MnP) and the laccase-mediator system with 1-hydroxybenzotriazole (HBT) as mediator can remove the estrogenic activities of the steroidal hormones 17beta-estradiol (E(2)) and ethinylestradiol (EE(2)). Using the yeast two-hybrid assay system, we confirmed that the estrogenic activities of E(2) and EE(2) are much higher than those of bisphenol A and nonylphenol. Greater than 80% of the estrogenic activities of E(2) and EE(2) were removed following 1-h treatment with MnP or the laccase-HBT system; extending the treatment time to 8h removed the remaining estrogenic activity of both steroidal hormones. HPLC analysis demonstrated that E(2) and EE(2) had disappeared almost completely in the reaction mixture after a 1-h treatment. These results strongly suggest that these ligninolytic enzymes are effective in removing the estrogenic activities of E(2) and EE(2).

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) formation was studied, in vitro, with two different chlorophenol mixtures (group “di+tri” 2,4-dichlorophenol; 2,3,4-, 2,3,5-, and 3,4,5-trichlorophenols and group “tri+tetra+penta” with 2,4,5-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol) and two different lignolytic enzymes, lignin and manganese peroxidase (LiP and MnP respectively), which can be found during the composting process of sewage sludge. The concentrations of PCDD/F in final samples are compared to the PCDD/F content of the control samples containing the chlorophenols. High increases were observed for experiments with MnP and phosphate buffer. Experiments that contained tri-, tetra- and pentachlorophenol with MnP resulted in more than 8 · 108 ng of OCDD kg−1 chlorophenol which was much higher than the initial amount (1 · 107 ng OCDD kg−1 chlorophenol). In relation to LiP experiments, only those at 37 °C showed a moderate increase (from 1.3 · 107 to 2.6 · 107 ng of OCDD kg−1 chlorophenol). The results agree with the literature in which high amounts of HpCDD and OCDD were found after a composting process and could explain the biogenic formation suggested by others, but the incidence on the total toxicity is less than that expected. The authors want to thank the University of Alicante for their economic support to perform this research and the project CTQ 2008-05520 of the Spanish Ministry of Science and Innovation, Prometeo 2009/043/FEDER of the Valencian Community of Spain.

28 p.-5 fig.-3 tab., Pleurotus ostreatus is an important edible mushroom and a model lignin degrading organism, whose genome contains nine genes of ligninolytic peroxidases, characteristic of white-rot fungi. These genes encode six manganese peroxidase (MnP) and three versatile peroxidase (VP) isoenzymes. Using liquid chromatography coupled to tandem mass spectrometry, secretion of four of these peroxidase isoenzymes (VP1, VP2, MnP2 and MnP6) was confirmed when P. ostreatus grows in a lignocellulose medium at 25 °C (three more isoenzymes were identified by only one unique peptide). Then, the effect of environmental parameters on the expression of the above nine genes was studied by reverse transcription-quantitative PCR by changing the incubation temperature and medium pH of P. ostreatus cultures pre-grown under the above conditions (using specific primers and two reference genes for result normalization). The cultures maintained at 25 °C (without pH adjustment) provided the highest levels of peroxidase transcripts and the highest total activity on Mn2+ (a substrate of both MnP and VP) and Reactive Black 5 (a VP specific substrate). The global analysis of the expression patterns divides peroxidase genes into three main groups according to the level of expression at optimal conditions (vp1/mnp3 > vp2/vp3/mnp1/mnp2/mnp6 > mnp4/mnp5). Decreasing or increasing the incubation temperature (to 10 °C or 37 °C) and adjusting the culture pH to acidic or alkaline conditions (pH 3 and 8) generally led to downregulation of most of the peroxidase genes (and decrease of the enzymatic activity), as shown when the transcription levels were referred to those found in the cultures maintained at the initial conditions. Temperature modification produced less dramatic effects than pH modification, with most genes being downregulated during the whole 10 °C treatment, while many of them were alternatively upregulated (often 6 h after the thermal shock) and downregulated (12 h) at 37 °C. Interestingly, mnp4 and mnp5 were the only peroxidase genes upregulated under alkaline pH conditions. The differences in the transcription levels of the peroxidase genes when the culture temperature and pH parameters were changed suggest an adaptive expression according to environmental conditions. Finally, the intracellular proteome was analyzed, under the same conditions used in the secretomic analysis, and the protein product of the highly-transcribed gene mnp3 was detected. Therefore, it was concluded that the absence of MnP3 from the secretome of the P. ostreatus lignocellulose cultures was related to impaired secretion., This work was supported by the PEROXICATS (KBBE-2010-4-265397; www.peroxicats.org) and INDOX (KBBE-2013-7-613549; www.indoxproject.eu) EU projects, and by the BIO2011-26694 and AGL2011-30495 projects of the Spanish Ministry of Economy and Competitiveness (MINECO). EF-F acknowledges a Junta de Ampliación de Estudios fellowship of the CSIC, co-funded by the European Social Fund, and FJR-D acknowledges a MINECO Ramón y Cajal contract.

Bisphenol A (BPA) and nonylphenol (NP) were treated with manganese peroxidase (MnP) and laccase prepared from the culture of lignin-degrading fungi. Laccase in the presence of 1-hydroxybenzotriazole (HBT), the so-called laccase-mediator system, was also applied to remove the estrogenic activity. Both chemicals disappeared in the reaction mixture within a 1-h treatment with MnP but the estrogenic activities of BPA and NP still remained 40% and 60% in the reaction mixtures after a 1-h and a 3-h treatment, respectively. Extension of the treatment time to 12 h completed the removal of estrogenic activities of BPA and NP. The laccase has less ability to remove these activities than MnP, but the laccase-HBT system was able to remove the activities in 6 h. A gel permeation chromatography (GPC) analysis revealed that main reaction products of BPA and NP may be oligomers formed by the action of enzymes. Enzymatic treatments extended to 48 h did not regenerate the estrogenic activities, suggesting that the ligninolytic enzymes are effective for the removal of the estrogenic activities of BPA and NP.

Lignocellulose is an abundant biomass that provides an alternative source for the production of renewable fuels and chemicals. The depolymerization of the carbohydrate polymers in lignocellulosic biomass is hindered by lignin, which is recalcitrant to chemical and biological degradation due to its complex chemical structure and linkage heterogeneity. The role of fungi in delignification due to the production of extracellular oxidative enzymes has been studied more extensively than that of bacteria. The two major groups of enzymes that are involved in lignin degradation are heme peroxidases and laccases. Lignin-degrading peroxidases include lignin peroxidase (LiP), manganese peroxidase (MnP), versatile peroxidase (VP), and dye-decolorizing peroxidase (DyP). LiP, MnP, and VP are class II extracellular fungal peroxidases that belong to the plant and microbial peroxidases superfamily. LiPs are strong oxidants with high-redox potential that oxidize the major non-phenolic structures of lignin. MnP is an Mn-dependent enzyme that catalyzes the oxidation of various phenolic substrates but is not capable of oxidizing the more recalcitrant non-phenolic lignin. VP enzymes combine the catalytic activities of both MnP and LiP and are able to oxidize Mn(2+) like MnP, and non-phenolic compounds like LiP. DyPs occur in both fungi and bacteria and are members of a new superfamily of heme peroxidases called DyPs. DyP enzymes oxidize high-redox potential anthraquinone dyes and were recently reported to oxidize lignin model compounds. The second major group of lignin-degrading enzymes, laccases, are found in plants, fungi, and bacteria and belong to the multicopper oxidase superfamily. They catalyze a one-electron oxidation with the concomitant four-electron reduction of molecular oxygen to water. Fungal laccases can oxidize phenolic lignin model compounds and have higher redox potential than bacterial laccases. In the presence of redox mediators, fungal laccases can oxidize non-phenolic lignin model compounds. In addition to the peroxidases and laccases, fungi produce other accessory oxidases such as aryl-alcohol oxidase and the glyoxal oxidase that generate the hydrogen peroxide required by the peroxidases. Lignin-degrading enzymes have attracted the attention for their valuable biotechnological applications especially in the pretreatment of recalcitrant lignocellulosic biomass for biofuel production. The use of lignin-degrading enzymes has been studied in various applications such as paper industry, textile industry, wastewater treatment and the degradation of herbicides.

A number of microorganisms, bacteria and filamentous fungi, are able to degrade lignocellulosic components to various extents. However, only a few ones can degrade lignins, among which wood-rotting fungi. White-rot fungi, the most frequent ones, mineralize cell wall components (cellulose, hemicelluloses and lignins) and extensively degrade lignins, which results in a bleached aspect of decayed wood. Fungal lignin degradation involves secreted heme-peroxidases and laccases that use oxidants as electron acceptors (H2O2 and O2). The three main heme-peroxidases are lignin peroxidases, manganese peroxidases and versatile peroxidases. Lignin and versatile peroxidases are able to oxidize non-phenolic lignin units. By contrast, manganese peroxidase needs diffusible Mn-chelated ions and mainly degrades lignin units with free phenolic groups. Other peroxidases have been recently found, such as dye peroxidases with potential applications in bioremediation and other industrial processes. Peroxidases need the cooperation of other oxidases such as glyoxal or aryl-alcohol oxidases to produce hydrogen peroxide. The recent availability of complete fungal genomes opens innovative opportunities to annotate lignocellulolytic gene families. Phylogenetic approaches are unique tools to comparatively analyse these data and predict or infer gene function. The increasing number of putative lignin-degrading enzymes emerging from genome analyses requires the development of high-throughput expression systems to meet the demands of industries. Several expression systems have been developed to produce more efficient recombinant ‘ligninases’ and auxiliary enzymes. Fungi and yeasts are useful hosts for the production of recombinant enzymes, but only a few ones are devoted to ligninase production. In this review, we give a survey of the main fungal and enzymatic actors of lignin degradation before discussing the phylogenetic inference strategy used to predict lignocellulolytic enzymes and reviewing the recombinant production of these enzymes in fungal hosts.

Multistage bleaching procedures using a combination of treatments with chlorine-based chemicals and alkaline extraction are normally used in bleaching kraft pulp, the most popular chemical pulp. There has been growing environmental concern about chlorinated organic substances, including toxic, mutagenic, and carcinogenic polychlorinated dioxins, dibenzofurans, and phenols, in the effluent from such bleaching of conventional kraft pulp. Today, general concern about the environmental impact of chlorine bleaching effluents has led to a trend toward elementary chlorine-free or totally chlorine-free bleaching methods. Biobleaching with white-rot fungi that can selectively degrade lignin in wood, has been studied by some workers to establish chlorine-free bleaching processes. Pretreatment with fungi has been shown to replace upto 70% of the chemicals needed to bleach kraft pulp. The usual specificity of biological reactions and their mild reaction conditions make biological delignification an interesting alternative to bleaching with chemicals such as pressurized oxygen or ozone. However, biobleaching with fungi is rather slow compared with chemical bleaching, and the cellulose in the pulp may be attacked by polysaccharideases. This chapter reviews the use of white-rot fungi to delignify and brighten kraft pulps. Manganese peroxidase, or laccase with a co-substrate, can demethylate and partially solubilize the lignin in pulps, mimicking the early steps of the fungal delignification.

Textile dyes are engineered to be resistant to environmental conditions. During recent years the treatment of textile dye effluents has been the focus of significant research because of the potentially low cost of the process. Mechanisms of biological textile dye decolorization depend greatly on the chemical structure of the dye and the microorganisms used. While basidiomycetous filamentous fungi are well recognized for dye decolorization through ligninolytic enzymes, reports on textile dye decolorization mechanisms of basidiomycetous yeasts have been scarce. Decolorization of several textile dyes by Trichosporon akiyoshidainum occurs during the first 12 h of cultivation. This fast decolorization process could not be solely related to siderophore production or dye sorption to biomass; it was shown to be a co-metabolic process. T. akiyoshidainum could use glucose, sucrose, and maltose as alternative carbon sources, and urea as an alternative nitrogen source with similar decolorization rates. The activity of two enzymes, manganese peroxidase and tyrosinase, were induced by the presence of dyes in the culture media, pointing to their potential role during the decolorization process. Manganese peroxidase titers reached 666 U l 1 to 10538 U l 1, while tyrosinase titers ranged between 84 U l 1 and 786 U l 1, depending on the dye tested. The present work provides a useful background to propose new ecofriendly alternatives for wastewater treatment in textile dying industries. Fil: Pajot, Hipólito Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Planta Piloto de Procesos Industriales Microbiológicos (i); Argentina Fil: Fariña, Julia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Planta Piloto de Procesos Industriales Microbiológicos (i); Argentina Fil: Castellanos de Figueroa, Lucia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Planta Piloto de Procesos Industriales Microbiológicos (i); Argentina. Universidad Nacional de Tucumán; Argentina

The development of bioremediation techniques with fungi has concentrated on their oxidative enzymes, and, more specifically, on the most important ligninolytic enzymes, namely laccase, lignin peroxidase (LiP), and manganese peroxidase (MnP). These enzymes are able to degrade, and even partially mineralize the most recalcitrant pollutants, such as textile dyes, endocrine disrupters (EDCs), polyaromatic hydrocarbons (PAHs), halogenated compounds, and various agrochemicals. These compounds can be found frequently in wastewaters or contaminated soil. The essential role of ligninolytic enzymes for the degradation of xenobiotics has been established repeatedly in liquid cultivations, but the correlation between the enzyme activity and biodegradation in soil systems has been very difficult to prove. Soil is a challenging matrix to study bioremediation with enzymes; as their activities are very low in soil, enzymes are typically bound to soil organic matter, and soil components may disturb the enzyme assays. Especially LiP activity is hard to detect from soil. Enzyme activities during bioremediation in field scale have not been measured and fungal enzyme preparations have not yet been utilized on a larger scale although several trials have been carried out with fungal cultures. The action of enzymes can be improved by several compounds called redox mediators, or by immobilization techniques.

11 págs, 5 figuras -- PAGS nros. 795-805, 2011 An exhaustive screening of the Pleurotus ostreatus genome was performed to search for nucleotide sequences of heme peroxidases in this white-rot fungus, which could be useful for different biotechnological applications. After sequence identification and manual curation of the corresponding genes and cDNAs, the deduced amino acid sequences were converted into structural homology models. A comparative study of these sequences and their structural models with those of known fungal peroxidases revealed the complete inventory of heme peroxidases of this fungus. This consists of cytochrome c peroxidase and ligninolytic peroxidases, including manganese peroxidase and versatile peroxidase but not lignin peroxidase, as representative of the ‘‘classical’’ superfamily of plant, fungal, and bacterial peroxidases; and members of two relatively ‘‘new’’ peroxidase superfamilies, namely heme-thiolate peroxidases, here described for the first time in a fungus from the genus Pleurotus, and dye-decolorizing peroxidases, already known in P. ostreatus but still to be thoroughly explored and characterized. the EU projects BIORENEW (NMP2-CT-2006-026456) and PEROXICATS (KBBE-2010-4-265397) and the Spanish project BIO2008-01533. The work conducted by the US Department of Energy Joint Genome Institute is supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231. E.F. thanks CSIC for a JAE fellowship and F.J.R.-D. thanks the Spanish MICINN for a Ramón y Cajal contract.

A new customer and environmental friendly method of hair bound dye decolouration was developed. Biotransformation of the azo-dyes Flame Orange and Ruby Red was studied using different oxidoreductases. The pathways of azo dye conversion by these enzymes were investigated and the intermediates and metabolites were identified and characterised using UV–vis spectroscopy, high-performance liquid chromatography (HPLC) and mass spectrometry (MS). Laccase from Pycnoporus cinnabarinus, manganese peroxidase (MnP) from Nematoloma frowardii and the novel Agrocybe aegerita peroxidase (AaP) were found to use a similar mechanism to convert azo dyes. They N-demethylated the dyes and concomitantly polymerized them to some extent. On the other hand the mechanism for cleavage of the azo bond by azo-reductases of Bacillus cereus and B. subtilis was based on reduction of the azo bond at the expense of NAD(P)H.