Litter of plant origin is the main source of soil organic matter, and its physical and chemical quality and decomposition rates are key variables in the prediction and modelling of how litter-derived ...carbon (C) is cycling through the ecosystem. However, the biological control factors for decomposition are not well understood and often poorly represented in global C models. These are typically run using simple parameters, such as nitrogen (N) and lignin concentrations, characterizing the quality of the organic matter input to soils and its accessibility to decomposer organisms. Manganese (Mn) is a key component for the formation of manganese peroxidase (MnP), an important enzyme for lignin degradation. However, the functional role of Mn on plant litter decomposition has been rarely experimentally examined. Here, using a forest and a cropland site we studied, over 41 months, the effects of Mn fertilization on MnP activity and decomposition of eight substrates ranging in initial lignin concentrations from 9.8 to 44.6%. Asymptotic decomposition models fitted the mass loss data best and allowed us to separately compare the influence of Mn fertilization on different litter stages and pools. Across substrates, Mn fertilization stimulated decomposition rates of the late stage where lignin dominates decomposition, resulting in smaller fraction of slowly decomposing litter. The increased MnP activity caused by Mn fertilization provided the mechanism explaining the stimulated decomposition in the Mn-addition treatments.
•Asymptotic decomposition models best fit data for remaining mass.•Mn fertilization stimulated decomposition rates in late stages of decomposition.•Increased decomposition rates in late stage of decomposition were clearly linked to the activity of manganese peroxidase.•Mn cycle in ecosystems has important implications for predicting C residence time in soil.
Display omitted
•Thirteen laccase isoforms in 3 sub-families identified in Cyathus bulleri.•Six manganese peroxidase isoforms identified in Cyathus bulleri.•Transcription profile of laccase and ...manganese peroxidase isoforms on wheat bran.•Delignification and saccharification of wheat straw and rice husk.
One of the major impediments in the use of agricultural by-products, including rice husk and wheat straw, as a raw material for biofuel production is the availability of a suitable biological method for delignification. The current physical, chemical and physico-chemical methods are harsh, expensive and are accompanied by the release of toxic end-products such as furan derivatives, weak carboxylic acids and phenolic compounds. The aim of this study was to explore the lignin degrading enzymes of Cyathus bulleri, an avid lignin degrader, for their use in delignification of agricultural by-products. A total of 13 laccase (Lcc) encoding and 6 manganese peroxidase or MnP (MnP) encoding genes were identified in the draft genome of C. bulleri. The Lcc genes could be sub-divided in to 3 classes based on their structural organization whereas no common structures were identified in the MnPs. Similarity at the genomic level for all laccases (except Lcc12) indicated their evolution as a result of gene duplication and these appeared to be very closely related based on the phylogenetic relationship. All the copper binding domains and the heme signature sequences were conserved in the laccases and the MnPs respectively. A transmembrane helix was predicted at the C-terminus of Lcc12 suggesting its localization on the mycelial surface. A temporal analysis of the transcription of Lcc and MnP genes was carried out on wheat bran (WB) and the data indicated Lcc1 to be transcribed the most on Day 4 while Lcc12 was transcribed during later stages of growth. The crude culture filtrate obtained from WB-grown fungus released reducing sugars from rice husk (∼18.5 mg/g of rice husk) and wheat straw (∼9.5 mg/g of WS) indicating effective delignification as well as saccharification of these materials.
Ligninolytic enzymes play a key role in degradation and detoxification of lignocellulosic waste in environment. The major ligninolytic enzymes are laccase, lignin peroxidase, manganese peroxidase, ...and versatile peroxidase. The activities of these enzymes are enhanced by various mediators as well as some other enzymes (feruloyl esterase, aryl-alcohol oxidase, quinone reductases, lipases, catechol 2, 3-dioxygenase) to facilitate the process for degradation and detoxification of lignocellulosic waste in environment. The structurally laccase is isoenzymes with monomeric or dimeric and glycosylation levels (10–45%). This contains four copper ions of three different types. The enzyme catalyzes the overall reaction: 4 benzenediol + O2 to 4 benzosemiquinone + 2H2O. While, lignin peroxidase is a glycoprotein molecular mass of 38–46 kDa containing one mole of iron protoporphyrin IX per one mol of protein, catalyzes the H2O2 dependent oxidative depolymerization of lignin. The manganese peroxidase is a glycosylated heme protein with molecular mass of 40–50kDa. It depolymerizes the lignin molecule in the presence of manganese ion. The versatile peroxidase has broad range substrate sharing typical features of the manganese and lignin peroxidase families. Although ligninolytic enzymes have broad range of industrial application specially the degradation and detoxification of lignocellulosic waste discharged from various industrial activities, its large scale application is still limited due to lack of limited production. Further, the extremophilic properties of ligninolytic enzymes indicated their broad prospects in varied environmental conditions. Therefore it needs more extensive research for understanding its structure and mechanisms for broad range commercial applications.
Laccase; Lignin peroxidase; Manganese peroxidase; Versatile peroxidase; Lignocellulosic waste; Degradation and detoxification, Environmental science, Microbiology.
Manganese (Mn) is a possibly critical yet poorly understood element controlling soil carbon (C) stocks. In temperate forests, Mn availability correlates strongly with organic C decay, but we know ...little about its role in soil organic matter decomposition in most terrestrial environments. In this study, we evaluate Mn in grassland C dynamics along a rainfall gradient in Hawaii. We measured Mn, organic matter, and microbial enzyme activities along the rainfall gradient to evaluate relationships among Mn oxidation state, chemical/biological reactivity, and soil C turnover. Neither Mn abundance nor its oxidation state are strong predictors of organic C instability along the grassland gradient. We also used an incubation experiment to investigate how dissolved organic C and CO2 release from the grassland soil respond to increased Mn bioavailability. We found that Mn availability did not correlate with soil C instability; Mn additions corresponded with lower dissolved organic C and CO2 fluxes from soils than did additions of deionized water. Mn availability may not predict soil C stability as well as previously thought.
•Manganese does not predict organic carbon loss from a Hawaiian grassland.•Manganese availability does not reduce organic carbon in a Hawaiian grassland soil.•Manganese does not control organic carbon decay in a Hawaiian grassland.
The hazardous effects of plastic and plastic leachates on organisms, even bacteria, have attracted widespread attention, but only a limited effort has been devoted to explore the response of fungi to ...plastic leachate induced by light irradiation. Here, we performed plastic leaching experiments to obtain leachates from polyethylene (PE), polyethylene terephthalate (PET) and polypropylene (PP), and optical properties of plastic leachates were analysed to determine the influence of light conditions and plastic materials on that. The effects of plastic leachates on the production of fungal enzyme and the biodegradation of heterocyclic dye by fungi were evaluated. Results indicated that the UV light greatly enhanced the release of leachates from the three plastics. Both plastic polymers and light irradiation affected the plastic-derived dissolved organic carbon (DOC) and their aromaticity, but the molecular weight of plastic leachates showed no dependency on light irradiation types, and PE was the easiest to photo age and leached more DOC. Plastic leachates had no dose-effect on the production of extracellular enzymes by fungi. PE leachates showed long-term toxicities to fungi, and no manganese peroxidase activities were detected after a 42-day incubation, while that of controls were up to 73.64 ± 8.81 U/L. However, the PE and PP leachates greatly promoted methylene blue degradation by the fungi, but PET leachates relieved the decolouration of methylene blue, probably because of the benzene ring structure in the PET monomer. Fusarium oxysporum had a stronger degradation ability than Phanerochaete chrysosporium. Our results indicate that plastic leachates can influence the production and secretion of fungi ligninolytic extracellular enzymes, and regulate the fungal degradation of heterocyclic dye.
Display omitted
•UV light enhanced the release of plastic leachates.•Plastic leachates had a long-term toxicity in fungi.•PE and PP leachates promoted methylene blue degradation by fungi.
A novel study on biodegradation of 30 mg L−1 of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) mixture (celecoxib, diclofenac and ibuprofen) by two wood-rot fungi; Ganoderma applanatum (GA) and ...Laetiporus sulphureus (LS) was investigated for 72 h. The removal efficiency of celecoxib, diclofenac and ibuprofen were 98, 96 and 95% by the fungal consortium (GA + LS). Although, both GA and LS exhibited low removal efficiency (61 and 73% respectively) on NSAIDs. However, 99.5% degradation of the drug mixture (NSAIDs) was achieved on the addition of the fungal consortium (GA + LS) to the experimental set-up. Overall, LS exhibited higher degradation efficiency; 92, 87, 79% on celecoxib, diclofenac and ibuprofen than GA with 89, 80 and 66% respectively. Enzyme analyses revealed significant induction of 201, 180 and 135% in laccase (Lac), lignin peroxidase (LiP) and manganese peroxidase (MnP) by the fungal consortium during degradation of the NSAIDs respectively. The experimental data showed the best goodness of fit when subjected to Langmuir (R2 = 0.980) and Temkin (R2 = 0.979) isotherm models which suggests monolayer and heterogeneous nature exhibited by the mycelia during interactions with NSAIDs. The degradation mechanism followed pseudo-second-order kinetic model (R2 = 0.987) indicating the strong influence of fungal biomass in the degradation of NSAIDs. Furthermore, Gas Chromatography-Mass Spectrometry (GCMS) and High-Performance Liquid Chromatography (HPLC) analyses confirmed the degraded metabolic states of the NSAIDs after treatment with GA, LS and consortium (GA + LS). Hence, the complete removal of NSAIDs is best achieved in an economical and eco-friendly way with the use of fungi consortium.
Cobiomass degradation of drug mixture (NSAIDs), enzyme systems and metabolite. Display omitted
•Successful co-degradation of NSAIDS by G. applanatum and L. sulphureus within 72 h.•Degradation efficiency of 99.5% was achieved on treatment of NSAIDs.•High induction of laccase revealed the significant role played during degradation.•Isotherm studies revealed the fungi's monolayer and heterogeneous nature.
The aim of the present work is to evaluate the ability of ‘fungi’ for the biodegradation of recalcitrant xenobiotic compound, ‘Atrazine’ in batch liquid cultures. Different parameters like pH ...(2.0–8.0) temperature (16–32 °C), biomass (1–5 g), and concentration (25–100 ppm) were optimized for the efficient degradation of atrazine. The decomposition behavior of atrazine is analyzed with the help of Fourier Transform Infrared (FTIR) spectroscopy. Herein, we have reported that the Bjerkandera adusta possess high removal efficiency of the xenobiotic compound (atrazine) up to 92%. The fungal strain investigated could prove to be a valuable active pesticide degrading micro-organism, with high detoxification values. These results are useful for improved understanding and prediction of the behavior and fate of B. adusta in the bio-purification of wastewater contaminated with xenobiotics. Thus providing a new and green approach for the remediation of toxicants without altering the environmental components.
Display omitted
•Role of Mycoremediation for the removal of agro-chemicals.•Appraising the behavior of Bjerkandera adusta for degradation of Atrazine.•Toxicity estimation test was performed for fungal treated contaminated water.•Developed method is, cost effective, eco-friendly for the waste water treatment.
A tetracycline degrading bacterial strains was characterized from the municipal sludge and detected its ability to produce manganese peroxidase. The molecular weight of manganese peroxidase was ...determined as 46 kDa after Biogel P-100 gel filtration column chromatography purification. Maximum tetracycline degradation was observed with the manganese peroxidase from the strain Bacillus velezensis Al-Dhabi 140 and the optimum degradation process was studied. Optimization revealed the maximum removal efficacy was obtained as 87 mg/L at initial tetracycline concentration 143.75 mg/L, pH 6.94 and 8.04% inoculum. Consequently, fibrous bed reactor containing the culture of B. velezensis Al-Dhabi 140 in fibrous matrix was formed to transform tetracycline in synthetic wastewater. The transformed product of tetracycline from the fibrous bed reactor was evident by the activity of ligninolytic enzymes produced by B. velezensis Al-Dhabi 140 in reactor. The decreased level of antibacterial potency was obtained after 10 days. The zone of inhibition was 24 ± 1 mm after 1 day and it decreased as 9 ± 1 mm after 10 days. Based on the findings, fibrous bed B. velezensis Al-Dhabi 140 could be an efficient strain for tetracycline removal from artificial wastewater, even from natural wastewater.
•Bacillus velezensis effectively degraded tetracycline.•Fibrous bed reactor coated B. velezensis converted tetracycline from wastewater.•Liginolytic manganese peroxidase induced the degradation of tetracycline.•B.velezensis treated water decreases tetracycline and enzyme level was strong.
Soil pollution by Petroleum contaminants are a major threat to the ecosystem that they are responsible for such dangers as mutation, carcinogenesis, and environmental toxicity. In this study, ...bioremediation of the bio-slurry reactor containing soil with different concentrations of pyrene were surveyed by transgenic
Pseudomonas putida
KT2440 (with manganese peroxidase 2 gene (
mnp2
) from
Pleurotus ostreatus
fungus). At first step of the study, five different genera were identified in the soil sample the most abundant genus belonged to
pseudomonas
. In the second step, soil bio-slurry reactors were treated with different concentration of pyrene (50, 100, 200, 400 ppm) for 1, 5, 10, 15, and 20 days. According to GC analysis, two concentrations of 100 ppm and 200 ppm of pyrene after 10 and 15 days of the treatment times were selected as optimum reactors. The efficiency of pyrene removal was investigated in bio-slurry reactors with wild-type and transgenic
Pseudomonas putida
KT2440. The results showed that the percentage of pyrene degradation for 100 and 200 ppm concentrations were 22.56%, 13.97%, 26.08%, and 15.59% in the bio-slurry reactors containing wild-type bacteria after 10 and 15 days of the treatment, respectively. Furthermore, the percentage of pyrene degradation for 100 and 200 ppm concentrations were 22.56%, 26.06%, 38.4%, and 23.74% in the bio-slurry reactors containing transgenic bacteria after 10 and 15 days of the treatment, respectively. Therefore, it seems that the bio-slurry reactor has more ability for pyrene bioremediation in the soil in the presence of the transgenic
Pseudomonas putida
KT2440 containing
mnp2
gene.
Triclosan (TCS) is extensively used in healthcare and personal care products as an antibacterial agent. Due to the persistent and toxic nature of TCS, it is not completely degraded in the biological ...wastewater treatment process. In this research work, identification of TCS degrading bacteria from municipal wastewater sludge and applying the same as bioaugmentation treatment for wastewater have been reported. Based on the 16S rRNA analysis of wastewater sludge, it was found that Providencia rettgeri MB-IIT strain was active and able to grow in higher TCS concentration. The identified bacterial strain was able to use TCS as carbon and energy source for its growth. The biodegradation experiment was optimized for the operational parameters viz. pH (5−10), inoculum size (1–5% (v/v)) and different initial concentration (2, 5, and 10 mg/L) of TCS. During the TCS degradation process, manganese peroxidase (MnP) and laccase (LAC) enzyme activity and specific growth rate of P. rettgeri strain were maximum at pH=7% and 2% (v/v) inoculum size, resulting in 98% of TCS removal efficiency. A total of six intermediate products were identified from the Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) analysis, and the two mechanisms responsible for the degradation of TCS have been elucidated. The study highlights that P. rettgeri MB-IIT strain could be advantageously used to degrade triclosan present in the wastewater.
Display omitted
•Triclosan degrading bacteria was isolated from municipal wastewater sludge.•Providencia rettgeri present in wastewater (sludge) was found to be efficient in degrading TCS.•Ether bond cleavage and dechlorination are the major degradation mechanisms.•Manganese peroxidase and laccase produced by P. rettgeri concurrently participate to degrade TCS.
PDF
