Ligninolytic Fungi Research Articles

Assessment of fungal and thermo-alkaline post-treatments of solid digestate in a recirculation scheme to increase flexibility in feedstocks supply management of biogas plants

Agricultural biogas plants can suffer occasional feedstock shortages (poor harvest, storage …) and recirculation of solid digestate (SD) into digester has been identified as a simple way to offset methane production loss from these situations. Calculations show that recirculation of SD could offset for losses in plant methane production by up to 2.4%. In that context, two post-treatments were evaluated to enhance residual potential methane of agricultural SD. Effect of fungal solid state fermentation (SSF) of SD on subsequent methane production has never been explored before. It was hypothesized that: (i) ligninolytic fungi would be able to specifically use the complex fraction of SD for their growth and (ii) energy generation from the subsequent anaerobic digestion of the colonized SD will be enhanced. However, experiments showed that thermo-alkaline treatment of SD (used as alkalinization and sterilization process) and a high spawn level (20% w/w) were necessary to perform fungal SSF. Besides, the observed fungal activities on SD did not target specifically the most complex fractions. This led to uncontrolled organic matter losses and subsequent decreases of biodegradability and methane yield of SD (up to 50%). Therefore, fungal SSF of SD before its recirculation into biogas plants appeared not to be a viable option. Only thermo-alkaline treatment (CaO 2% w/w and 121 °C 30 min) enhanced methane yield of SD by 13% and decreased its complex fraction by 25%. Further studies on optimization of this post-treatment may enhance efficiency of SD recirculation strategy to offset plant methane production losses.

Enzymatic Hydrolysis of Two-way Pretreated Sawdust of <i>Eucalyptus globulus</i> and <i>Cupressus lusitanica</i>

Sawdust in Ethiopia, despite of its abundance, is not being properly utilized. Pre-treatment has been found to be crucial step before enzymatic hydrolysis of lignocellulosic resources to obtain sugars from such resources. Various pre-treatment methods have been developed to facilitate these bio-conversion processes. This research was aimed at investigating the effects of the combined pretreatments of steam and mild NaOH with white rot fungi (WRF) on sawdust samples from Eucalyptus globulus and Cupressus lusitanica were investigated. The amounts of losses of lignin, cellulose and hemicellulose contents of the pretreated sawdust samples were measured. Samples of the pretreated sawdust samples were then subjected to the enzymes from the hydrolytic wood rot fungi for hydrolysis into fermentable sugars. It was observed that lignin, cellulose and hemicellulose losses of the two sawdust types increased with the increasing incubation days but lignin and hemicellulose were preferentially degraded than cellulose. Sugar yield obtained from the sawdust pretreated in the combination of NaOH with WRF and steam with WRF was significantly higher compared to the yield obtained from the NaOH and steam alone pretreated sawdust samples. Pretreatment by the combination of NaOH with the wood rot fungi significantly modified the recalcitrance nature of the sawdust samples than when steam combined with the fungi. Similarly, with increasing enzymatic hydrolysis periods, sugar yields significantly increased. Higher sugar yields were obtained from sawdust samples of E. globulus than C. lusitanica. The ligninolytic and cellulolytic fungi tested resulted in a notable sugar yields indicating the possible application of the wood rot fungi in sugar production from lignocellulosic sawdust wastes which could be used for different industrial applications.

Functional diversity of ligninolytic fungi associated with leaf litter decomposition

AbstractFungi play central roles in leaf litter decomposition as they are capable of actively decomposing lignin and other recalcitrant components in leaf litter that impact the decomposition in terrestrial ecosystems. Quantitative evaluation is lacking, however, regarding the ability of diverse fungi to decompose leaf litter and the variability of ligninolytic activity among fungal taxa. In this comprehensive synthesis, I summarize the data of 1,232 individual pure culture tests conducted under standardized protocols to examine the functional diversity of fungi associated with leaf litter decomposition, with special emphasis on the ligninolytic activity. Fungal strains tested included 218 species in 69 families of Basidiomycota, Ascomycota, and Mucoromycotina that were derived from tropical and temperate forests to polar tundra. Fungal strains were inoculated adjacent to sterilized leaves and other substrata and incubated in the laboratory in order (a) to examine their functional potentialities in terms of the ability to cause mass loss of leaves and decompose recalcitrant components and (b) to explore the effect of litter quality and various environmental factors. The results of these tests revealed that ligninolytic abilities were specifically detected in fungal strains in such families as Mycenaceae and Marasmiaceae in Basidiomycota, and Rhytismataceae and Xylariaceae in Ascomycota. The ligninolytic activity varied among fungal taxa and with the quality and type of substrata, incubation temperature, and external supply of nutrients. This review provides integrative accounts of the functional diversity of ligninolytic fungi associated with leaf litter decomposition and enhances our understanding of the roles of fungal diversity in decomposition processes.

AGING IN LIGNINOLYTIC FUNGI IN SPACE CONDITIONS

Aging is considered in the context of various abiotic stresses, such as water deficit, high temperature, salinity, cold, heavy metals, mechanical wounding, UV radiation, etc. It is well known that the extreme level of these factors can be reflected in sharply increased production of reactive oxygen species. Reactive oxygen species interact with cellular biomolecules, such as lipids, proteins and DNA and can play an important role in cell injury. At the same time, fungi are an appropriate model system in different research areas, including aging. Testing of ligninolytic fungi in space conditions is forthcoming. However, it is unknown how the conditions of microgravity would affect fungal cell aging and enzyme production. Determination of the long-term physiological responses and adaptation to the space environment is of great importance for fungal enzyme production as well.

Biodegradation of the endocrine disrupter 4-t-octylphenol by the non-ligninolytic fungus Fusarium falciforme RRK20: Process optimization, estrogenicity assessment, metabolite identification and proposed pathways

4-t-octylphenol (4-t-OP), a well-known endocrine disrupting compound, is frequently found in various environmental compartments at levels that may cause adverse effects to the ecosystem and public health. To date, most of the studies that investigate microbial transformations of 4-t-OP have focused on the process mediated by bacteria, ligninolytic fungi, or microbial consortia. There is no report on the complete degradation mechanism of 4-t-OP by non-ligninolytic fungi. In this study, we conducted laboratory experiments to explore and characterize the non-ligninolytic fungal strain Fusarium falciforme RRK20 to degrade 4-t-OP. Using the response surface methodology, the initial biomass concentration and temperature were the factors identified to be more influential on the efficiency of the biodegradation process as compared with pH. Under the optimized conditions (i.e., 28 °C, pH 6.5 with an initial inoculum density of 0.6 g L−1), 25 mg L−1 4-t-OP served as sole carbon source was completely depleted within a 14-d incubation; addition of low dosage of glucose was shown to significantly accelerate 4-t-OP degradation. The yeast estrogenic screening assay further confirmed the loss of estrogenic activity during the biodegradation process, though a longer incubation period was required for complete removal of estrogenicity. Metabolites identified by LC-MS/MS revealed that strain RRK20 might degrade 4-t-OP as sole energy source via alkyl chain oxidation and aromatic ring hydroxylation pathways. Together, these results not only suggest the potential use of non-ligninolytic fungi like strain RRK20 in remediation of 4-t-OP contaminated environments but may also improve our understanding of the environmental fate of 4-t-OP.

Biodegradation of styrofoam waste by ligninolytic fungi and bacteria

Styrofoam wastes are composed of many polymerized styrene monomers that are generally considered to be recalcitrant and are resistant to biodegradation. In this study, the ability of ligninolytic fungi and bacteria were investigated on degradation of styrofoam wastes. All the fungi and bacteria used were able to grow on agar media containing styrofoam. Fungi Cymatoderma dendriticum WM01, Ceriporia sp. BIOM3, and Pestalotiopsis sp. NG007 degraded 15.7%, 19.4%, and 74.4% styrofoam within 30 d, respectively. Cerratia marcescens BLSP4, Bacillus subtilis BLSP4, and Pseudomonas aeruginosa BLSP4 degraded 38.3%, 52.6%, and 63.4% styrofoam, respectively. SEM analysis demonstrated the appearance of micro pore in styrofoams treated with Pestalotiopsis sp. NG007 and P. aeruginosa indicating biodegradation. In addition, analysis using UATR FTIR corroborated removal of some functional groups from the degraded styrofoam were eliminated. This study showed strains of ligninolytic fungi and selected bacteria have the potential to be used in bioremediation of styrofoam wastes.

Neopestalotiopsis species presenting wide dye destaining activity: report of a mycelium-associated laccase

Wastewaters from textile dyeing industries represent an ecological concern, notably due to the known toxicity of azo dyes to the local microbiome and human health. Although physicochemical approaches are the rule for the treatment of industrial effluents, biological strategies such as enzyme-mediated dye destaining is a promising alternative. Notwithstanding a broad range of microorganisms, including fungi, algae, yeast, and bacteria, display dye-destaining properties, most of the literature has focused in ligninolytic fungi, leaving other classes of organisms somehow ignored. In this study, six endophytic strains isolated from Maytenus ilicifolia were studied for their destaining activity. The phylogenetic and morphological analysis allowed the identification of strain LGMF1504 as Neopestalotiopsis sp. LGMF1504 that decolorized several commercial dyes as the result of a mycelium-associated laccase. The enzyme expression was modulated by carbon and nitrogen content in the culture medium, it was weakly affected by the presence of aromatic compounds and metal ions while some common laccase mediators improved the destaining activity onto dye substrates. The best culture condition observed for laccase activity was a basic culture medium containing 5 g L−1 starch and 15 g L−1 ammonium tartrate. The laccase activity showed low substrate specificity and almost unaltered performance in a wide range of pH values and NaCl concentrations, suggesting the potential of Neopestalotiopsis sp. LGMF1504 for biodegradation approaches.

Analysis of decolorization potential of Myrothecium roridum in the light of its secretome and toxicological studies

To identify the enzymes potentially useful for the decolorization of azo dyes, the secretome of the ascomycetous fungus Myrothecium roridum IM6482 was studied by using a bottom-up proteomic approach. Among the identified proteins, the most promising for dye removal was laccase, which decolorized respectively, 66, 91, 79, and 80% of Acid Blue 113 (AB 113), Acid Red 27 (AR 27), Direct Blue 14 (DB 14), and Acid Orange 7 (AO 7). The degradation of dyes was enhanced at the wide range of pH from 4 to 8. The addition of redox mediators allowed eliminating AB 113 in concentrations up to 400 mg/L and decolorization of the simulated textile effluent. Microbial toxicity and phytotoxicity tests indicated that dyes are converted into low-toxicity metabolites. This is the first insight into the M. roridum secretome, its identification and its application for removal of select azo dyes. Obtained results extended knowledge concerning biodegradative potential of ascomycetous, ligninolytic fungi and will contribute to the improvement of dye removal by fungi.

Biochar and hydrochar from waste biomass promote the growth and enzyme activity of soil-resident ligninolytic fungi

Biochar (BC) and hydrochar (HC) are carbonaceous products obtained through, respectively, pyrolysis and hydrothermal carbonization processes of biomass. Both materials are multi-functional soil amendments. Ligninolytic fungi are primary decomposers of recalcitrant lignocellulosic material in nature through their extensive hyphal network and enzymes. In this work, two BC samples from red spruce pellets (BCSP) and grapevine pruning residues (BCGV) and two HC samples from urban pruning residues (HCUP) and the organic fraction of solid urban wastes (HCSU) were tested at concentrations of 0.4% and 2% (w/v) on the growth and enzyme activity of Trametes versicolor, Pleurotus ostreatus and Pleurotus eryngii. In all treatments with the lower concentration, BC and HC significantly stimulated fungal growth (up to about 90% increase for HCSU on T. versicolor), whereas at the higher dose some inhibition was observed on T. versicolor by BCSP and P. ostreatus by BCSP, BCGV and HCUP. The two materials, especially HC, at both doses noticeably increased the activity of laccase from T. versicolor and P. eryngii, up to 21 and 13 times, respectively, for HCUP compared to controls. The activity of manganese peroxidase from P. ostreatus was also greatly stimulated by BC and HC, especially when added at the higher concentration. The overall results obtained in this study suggest potential benefits for ligninolytic fungi from the presence of these materials in soil at adequate dose of application.

Effect of Induced Compost by Cellulolitic (Aspergillus fumigatus) and Ligninolitic (Geotrichum sp.) Fungi Inoculum Application on Vegetative Growth of Red Chili (Capsicum annuum L.)

Green waste (GW) is an important fraction of municipal solid waste (MSW). The composting of lignocellulosic GW is challenging due to its low decomposition rate. Therefore the use of fungi inoculum as a decomposer inducer on GW composting needs to study. The purpose of this study was to explore the potential of the compost induced by cellulolytic (Aspergillus fumigatus) and ligninolytic fungi (Geotrichum sp.) inoculum application on vegetative growth of red chilly plants (Capsicum annuum l.). This research was conducted in the green house of the Faculty of Agriculture the University of Lampung, Indonesia. Completely Randomized Design was adopted with five treatment dose of cellulolytic and ligninolytic compost amandmend of 0%, 10%, and 20% each (K= control, S1= Cellulose 10%, S2= cellulose 20%, L1= Ligninolytic 10% and L2= ligninolytic 20%). Parameters observed were plant height, dry weight, relative water content and chlorophyll of a, b and total. The results demonstrated that compost induced by cellulolytic fungi (Aspergilus fumigatus) and ligninolytic (Geotrichum sp) produced the optimal effect on growth parameters across all treatments. The compost application could increase significantly plant height, dry weight, relative water content. But not the chlorophyll content of a, b and total. The maximum measurements of plant height, dry weight, relative water content was achieved by S2, L2, L2, K and L2 treatments respectively. These results suggest that the inoculum induced compost has bene cial impacts for the use as organic fertilizer to enhance vegetative growth.

Pretreatment of wheat straw with ligninolytic fungi for increased biogas productivity

Biogas production from the agriculture waste biomass is a sustainable approach to managing the energy demand in the future. To do so, pretreatment is needed to remove lignin from the agribiomass to make it easily digestible substrate for the fermentative organisms. The current study was carried out to screen the most effective lignin-degrading fungal culture from their natural habitat. Pretreatment with robust ligninolytic fungi could be an efficient and economical method to degrade lignin. The presence of lignin in lignocellulosic biomass is the rate-limiting factor which reduces the biogas production. So, the best fungal strains were selected based on maximal Azure B dye decolorization. The strains were actively producing lignin peroxidases and laccases and decreased 48.2% of lignin from the wheat straw (WS) within 7 days of batch incubation. The scanning electron micrograph demonstrated visible degradation only in the fungi-treated wheat straw. The ligninolytic fungal culture pretreatment of WS enhanced the biogas yield five times compared with the untreated WS sample. Notably, these fast-acting lignin-degrading fungi gave a biogas yield with a short pretreatment time and additionally reduced the lag phase during the anaerobic digestion process. These findings showed that pretreatment with natural ligninolytic fungi could be considered as a less expensive method. The treatment is also effective in increasing the digestibility of lignocellulosic biomass and suitable for biogas production.

Screening white-rot fungi for bioremediation potential of 2,3,7,8-tetrachlorodibenzo-p-dioxin

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.

Understanding the role of mediators in the efficiency of advanced oxidation processes using white-rot fungi

Τhe coupling of biological with advanced oxidation processes for the removal of 13 pharmaceuticals is reported in this study. The efficiency of this system was examined by using two ligninolytic fungi, Trametes versicolor and Ganoderma lucidum. Pharmaceuticals’ removal was examined by using four different quinone substances (1,4-benzoquinone, 2,6-dimethoxy-1,4-benzoquinone, 2-methyl-1,4-naphthoquinone and gallic acid). The quinone redox cycling mechanism of the fungal species promotes the production of hydrogen peroxide for subsequent decomposition to non-selective and highly oxidizing hydroxyl radicals in presence of Fe(III)-oxalate. Results evidenced that the most effective mediators for T. versicolor and G. lucidum were 2,6-dimethoxy-1,4-benzoquinone (DMBQ) and gallic acid (GA), respectively. Time-course experiments showed that higher concentrations of Fe(II) were produced using DMBQ and GA, suggesting that the efficiency of the mediator in reducing Fe(III) is linked to the removal of pharmaceuticals. The application of DMBQ in the redox cycling process of T. versicolor resulted to 60–100% removal for all the pharmaceuticals, due to the high affinity of laccase enzyme for DMBQH2. The advanced bio-oxidation of T. versicolor was tested for hospital wastewater treatment. Results showed a decrease of the elimination degree for pharmaceuticals as compared to the previous bioassays conducted with a synthetic medium. Nevertheless, significant removals (30–100%) were achieved by using DMBQ and GA as mediators of the redox cycle for T. versicolor under the non-sterilized conditions of the hospital wastewater. The use of GA is of great importance since its phenolic form, equivalent to the hydroquinone form, is considered as a critical parameter in Fe(III) reduction.

The Role of Ligninolytic Enzymes Laccase and a Versatile Peroxidase of the White‐Rot Fungus Lentinus tigrinus in Biotransformation of Soil Humic Matter: Comparative In Vivo Study

AbstractSoil organic matter (SOM) turnover by ligninolytic fungi is a large‐scale process that controls organic carbon geochemistry in terrestrial ecosystems. However, the role of certain oxidative enzymes (e.g., laccase) in humus degradation remains unclear, as well as the molecular structure and recalcitrance of SOM components. In order to address these questions, the degradation of forest soil humic acid (HA) in the presence of laccase and a versatile peroxidase (VP) has been studied in the liquid culture of Lentinus tigrinus. Contrary to the evolving views on humus structure, we have found that alkali‐extractable and acid‐insoluble constituents of SOM (HA) contain true macromolecular components, stable in the presence of 0.1% sodium dodecyl sulfate but degradable/resynthesizable by oxidative enzymes acting on covalent linkages. The HA degradation in the presence of laccase (high N medium) occurs at slower initial rate than in the presence of VP (low N medium). However, each of the enzymes caused about 60% color loss and almost complete degradation of HA into smaller molecules (gel‐filtration data) within 2 weeks of cultivation. Depolymerization of HA in the culture liquid in the presence of laccase was accompanied by polymerization of degradation products on mycelium. Our results show that (1) humus macromolecules are not stable to oxidative enzymes once desorbed from the mineral phase, (2) laccase of Lentinus tigrinus is comparable by its degradation potential to VP, and (3) interfacial secondary synthesis reactions occur during humus decay in the presence of laccase. Our results highlight the important role of laccases in SOM sequestration in soils.

Evaluating the scale-up of a reactor for the treatment of textile effluents using Bjerkandera sp

Effluents from the textile industry have a negative environmental impact due to their high load of dyes and hard-to-remove compounds: additives, detergents, and surfactants; these must be treated before effluents can be discharged into water. White-rot fungi show great potential for the bioremediation of water and soil matrices contaminated with recalcitrant pollutants (these are generally toxic). In this work, we designed a 5 L fixed bed reactor and evaluated its performance on the degradation of pollutants in effluents from the textile industry in continuous-operation mode under non-sterile conditions, using ligninolytic fungus Bjerkandera sp. (anamorphic state R1). This setup was based on a previous design of a 0.25 L fixed-bed model bioreactor. The system was designed by taking into account the geometric and hydrodynamic similarities of both setups. In continuous-mode color-removal assays, the bioreactor was operated at a 36 h Hydraulic retention time (HRT), a 1 L/min air flux at 33 °C, and a dye concentration of 75 g/L (sulfur black 1) and 6.5 g/L (indigo Vat blue 1). 69% of the dye was removed, and changes in the chemical structures of the dyes confirmed the ligninolytic activity of the microorganism as the main dye removal mechanism.

The potential of fungal co-cultures as biological inducers for increased ligninolytic enzymes on agricultural residues

Dual cultivation or co-cultivation of fungi and the exploitation of interspecific interaction, even antagonism, show considerable promise as a strategy in enhancing enzyme production. The aim of this work was to investigate the phenomenon of antagonistic invasion as a strategy to possibly accelerate secondary metabolism in ligninolytic fungi and thereby to increase enzyme activity. Ten different fungal strains were cultivated on various substrates like corn cob, wheat straw and sugar cane bagasse and evaluated for the effects of invasion antagonistic interaction on enzyme production. Monoculture enzyme activities were compared with co-culture enzyme activities. However, strains such as Trichoderma sp. KN10, Rhizopus microsporus KN2, Fomitopsis sp. KN1 and Coriolopsis sp. KN6 demonstrated strong tendencies of invasion and replacement in co-cultures. Also, significant changes in morphology and concomitant increase in enzyme activity were demonstrated in a majority of these interactions with remarkable results observed with invasions involving Trichoderma sp. KN10. Analysis of mean values of enzyme activity showed dual culture interactions involving KN10 with values for manganese peroxidase production approximately at 1.46 U/mL compared to monoculture of 0.06 U/mL. Furthermore, dual culture laccase values were approximately 0.09 U/mL compared to monocultures of 0.05 U/mL. Overall, the highest enzyme activity was observed using wheat straw reflecting similar patterns of invasion interactions. This study demonstrates that dual cultivation of fungi with the appropriate substrates results in improved production of biotechnologically relevant enzymes.

A comparison of ergosterol and PLFA methods for monitoring the growth of ligninolytic fungi during wheat straw solid state cultivation

Ergosterol, total phospholipid fatty acid (PLFA) and linoleic acid (18:2n-6) have all been used to determine fungal growth. This paper compares these methods to assess the growth of four different saprotrophic fungal species during solid state cultivation using a wheat straw substrate that have not been compared or measured previously. Ergosterol production appeared to track the mycelia growth well but its production differed considerably between fungi. This means that a specific conversion factor needs to be determined and applied for any given fungus. In comparison, measurements of total PLFA and linoleic acid only showed promise for determining the growth of Postia placenta due to the positive correlation with ergosterol measurements. In contrast, the other fungi tested (Phanerochaete chrysosporium, Serpula lacrymans and Schizophyllum commune) showed either no correlation or in some cases a negative correlation using this assay. The novel findings highlight the variation in fungal fatty acid between species, culture conditions and durations of incubation; suggesting that measurement of linoleic acid is only usable in specific cases. These findings provide important consideration for the study of fungi growing in solid substrates and suggest that the use of PLFA might bias diversity indices.

Degradation of polycyclic aromatic hydrocarbons (phenanthrene and pyrene) by the ligninolytic fungi Ganoderma lucidum isolated from the hardwood stump

BackgroundDue to progress in science and technology, several harmful polycyclic aromatic hydrocarbons are synthesized and released into the environment. In the present investigation, a phenanthrene- and pyrene-degrading white rot fungi Ganoderma lucidum strain CCG1 was isolated from the Janjgir Champa district of Chhattisgarh, India, and then the degradation of phenanthrene and pyrene was estimated by high-performance liquid chromatography.ResultsIt was found that G. lucidum able to degrade 99.65% of 20 mg/L of phenanthrene and 99.58% of pyrene in mineral salt broth after 30th day of incubation at 27 °C. G. lucidum produced significant amounts (p < 0.0001) of ligninolytic enzymes (Laccase, lignin peroxidase and manganese peroxidase) in the phenanthrene- and pyrene-containing mineral salt broth. G. lucidum produced maximum 10,788.00 U/L laccase, 3283.00 U/L Lignin peroxidase and 47,444.00 U/L Manganese peroxidase enzymes in the presence of phenanthrene and produced maximum 10,166.00 U/L laccase, 3613.00 U/L lignin peroxidase and 50,977.00 U/L manganese peroxidase enzymes in the presence of pyrene. Therefore, G. lucidum will be a potent phenanthrene and pyrene degrader from the environment.

Decolorization of Remazol Brilliant Blue R by laccase of newly isolated Leiotrametes flavida Strain ZUL62 from Bangka Heath Forest, Indonesia

Falah S, Sari NM, Hidayat A. 2018. Decolorization of Remazol Brilliant Blue R by laccase of newly isolated Leiotrametes flavida Strain ZUL62 from Bangka Heath Forest, Indonesia. Biodiversitas 19: 633-639. The use of microbial enzymes seems to be an appropriate approach to neutralize synthetic dyes, providing an eco-friendly and cost-competitive alternative solution for treating industrial effluents. The objective of this research was to select the most potential fungal isolate with high laccase activity to decolorize Remazol Brilliant Blue R (RBBR) synthetic dyes. The isolation of fungal body and sampling of wood decay specimens were conducted in six different locations in heath (kerangas) forest of Bangka Belitung, Indonesia. In the present study, a total of 13 isolates were screened by using indicator plate method and for their enzyme activity. The preliminary screening was done to screen ligninolytic fungi. Then the primary screening using various indicator compounds was conducted to select laccases-producing fungi. The enzyme activity assay was performed to select fungal isolate with the highest activity. We found that the most potential fungi belonged to Leiotrametes flavida Strain ZUL62, which had been confirmed by molecular identification using 5.8S rDNA/ITS analysis. In addition, the laccase from Leiotrametes flavida Strain ZUL62 could decolorize RBBR, exhibiting a high rate of decolorization rate of 62% without any mediator within 24 h of incubation. To our best of knowledge, this study represented the first report about Leiotrametes flavida Strain ZUL62 and its potential laccase enzyme for dyes effluent treatment.

Ligninolytic basidiomycetes as promising organisms for the mycoremediation of PAH-contaminated Environments

Primary screening of ligninolytic fungi belonging to wood- and soil-inhabiting basidiomycetes revealed their ability to degrade three-ringed PAHs with formation of quinone metabolites at the first stage. The degradative activity was both species and strain specific, and some differences in the “chances” for the formed quinones were found. They were the main end metabolites in the degradation of PAHs by Stropharia rugosoannulata and Agaricus bisporus. During PAH degradation by strains of Trametes versicolor, Pleurotus ostreatus, Schizophyllum commune, and Bjerkandera adusta similar metabolites were detected during the cultivation, but they were utilized further. The results supported the hypothesis that the degree of PAH degradation may depend on the composition of the extracellular ligninolytic complex of the fungi: in the presence of a single ligninolytic enzyme, laccase, the accumulation of quinone metabolites takes place; their further utilization is possible with the participation of ligninolytic peroxidases. The data obtained showed the necessity not only to identify the metabolites formed, but also to study the activity of the basic ligninolytic enzymes. It is important for the correct selection of fungal strains for mycoremediation.