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•B. adusta DH0817 removed 59.7 % of SDZ at 10 °C within 20 days.•Six SDZ biodegradation pathways and their intermediates biotoxicity were proposed.•SDZ biodegradation by DH0817 was ...predominantly driven by CYP450.•The transcriptomics of DH0817 responding to low temperatures and SDZ were analyzed.
The prolonged period of low temperatures in northern China poses a significant challenge to the bioremediation of antibiotic pollution. This study reports that a white-rot fungus Bjerkandera adusta DH0817, isolated from a poultry farm in Liaoning Province, can remove 60 % of SDZ within 20 days at 10°C and reduce the biotoxicity of SDZ. Six degradation pathways were proposed. SDZ biodegradation was primarily driven by cytochrome P450. Transcriptome analysis revealed that DH0817 upregulated genes associated with cell membrane, transcription factors and soluble sugars in response to low temperatures. Subsequently, genes associated with fatty acid, proteins and enzymes were upregulated to remove SDZ at low temperatures. This study provides valuable microbial resources and serves as a theoretical reference for addressing antibiotic pollution in livestock and poultry farms under low temperature conditions.
The ability of some white rot basidiomycetes to remove lignin selectively from wood indicates that low molecular weight oxidants have a role in ligninolysis. These oxidants are likely free radicals ...generated by fungal peroxidases from compounds in the biodegrading wood. Past work supports a role for manganese peroxidases (MnPs) in the production of ligninolytic oxidants from fungal membrane lipids. However, the fatty acid alkylperoxyl radicals initially formed during this process are not reactive enough to attack the major structures in lignin. Here, we evaluate the hypothesis that the peroxidation of fatty aldehydes might provide a source of more reactive acylperoxyl radicals. We found that
produced
2-nonenal,
octenal, and n-hexanal (a likely metabolite of
2,4-decadienal) during the incipient decay of aspen wood. Fungal fatty aldehydes supported the
oxidation by MnPs of a nonphenolic lignin model dimer, and also of the monomeric model veratryl alcohol. Experiments with the latter compound showed that the reactions were partially inhibited by oxalate, the chelator that white rot fungi employ to detach Mn
from the MnP active site, but nevertheless proceeded at its physiological concentration of 1 mM. The addition of catalase was inhibitory, which suggests that the standard MnP catalytic cycle is involved in the oxidation of aldehydes. MnP oxidized
2-nonenal quantitatively to
2-nonenoic acid with the consumption of one O
equivalent. The data suggest that when Mn
remains associated with MnP, it can oxidize aldehydes to their acyl radicals, and the latter subsequently add O
to become ligninolytic acylperoxyl radicals.IMPORTANCEThe biodegradation of lignin by white rot fungi is essential for the natural recycling of plant biomass and has useful applications in lignocellulose bioprocessing. Although fungal peroxidases have a key role in ligninolysis, past work indicates that biodegradation is initiated by smaller, as yet unidentified oxidants that can infiltrate the substrate. Here, we present evidence that the peroxidase-catalyzed oxidation of naturally occurring fungal aldehydes may provide a source of ligninolytic free radical oxidants.
Aim
In this study, the biological variation for improvement of the nutritive value of wheat straw by 12 Ceriporiopsis subvermispora, 10 Pleurotus eryngii and 10 Lentinula edodes strains was assessed. ...Screening of the best performing strains within each species was made based on the in vitro degradability of fungal‐treated wheat straw.
Methods and Results
Wheat straw was inoculated with each strain for 7 weeks of solid state fermentation. Weekly samples were evaluated for in vitro gas production (IVGP) in buffered rumen fluid for 72 h. Out of the 32 fungal strains studied, 17 strains showed a significantly higher (P < 0·05) IVGP compared to the control after 7 weeks (227·7 ml g−1 OM). The three best Ceriporiopsis subvermispora strains showed a mean IVGP of 297·0 ml g−1 OM, while the three best P. eryngii and L. edodes strains showed a mean IVGP of 257·8 and 291·5 ml g−1 OM, respectively.
Conclusion
Ceriporiopsis subvermispora strains show an overall high potential to improve the ruminal degradability of wheat straw, followed by L. edodes and P. eryngii strains.
Significance and Impact of the Study
Large variation exists within and among different fungal species in the valorization of wheat straw, which offers opportunities to improve the fungal genotype by breeding.
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•Combined addition of Cu2+ and Mn2+ improves solid-state fungal pretreatment.•Unexpected effect of Cu2+ and Mn2+ on non-laccase-producing P.chrysosporium.•Enhanced and prolonged MnP ...activities by CuSO4 and MnSO4 supplementation.•Significantly improved degree and selectivity of delignification.•Glucose yield almost three times higher compared to non-supplemented system.
Biological pretreatment of lignocellulose by white-rot fungi is an environmentally friendly alternative to chemical and physical approaches to enhance enzymatic saccharification. However, inefficient lignin degradation and substantial cellulose consumption during fungal pretreatment can cause low sugar yields. In this study, the combined action of CuSO4 and MnSO4 effectively improved the degree and selectivity of delignification during solid-state fungal pretreatment of poplar wood by Phanerochaete chrysosporium. Compared to pretreatment without this supplementation, a 1.9 fold higher lignin degradation and 2.4 times higher delignification selectivity value were obtained due to the increased and prolonged manganese peroxidase activity. Enzymatic saccharification of supplemented pretreated wood resulted in a 2.9 times higher glucose yield compared to the non-supplemented system. This study has demonstrated that the combined application of Mn2+ and Cu2+ can significantly improve the fungal pretreatment process and that the beneficial effect of Cu2+ on delignification is not restricted to laccase-producing fungi.
Acacia spp. are invasive in Southern Europe, and their high propagation rates produce excessive biomass, exacerbating wildfire risk. However, lignocellulosic biomass from Acacia spp. may be utilised ...for diverse biorefinery applications. In this study, attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR), high-performance anion-exchange chromatography pulsed amperometric detection (HPAEC-PAD) and lignin content determinations were used for a comparative compositional characterisation of A. dealbata, A. longifolia and A. melanoxylon. Additionally, biomass was treated with three white-rot fungi species (Ganoderma lucidum, Pleurotus ostreatus and Trametes versicolor), which preferentially degrade lignin. Our results showed that the pre-treatments do not significantly alter neutral sugar composition while reducing lignin content. Sugar release from enzymatic saccharification was enhanced, in some cases possibly due to a synergy between white-rot fungi and mild alkali pretreatments. For example, in A. dealbata stems treated with alkali and P. ostreatus, saccharification yield was 702.3 nmol mg−1, which is higher than the samples treated only with alkali (608.1 nmol mg−1), and 2.9-fold higher than the non-pretreated controls (243.9 nmol mg−1). By characterising biomass and pretreatments, generated data creates value for unused biomass resources, contributing to the implementation of sustainable biorefining systems. In due course, the generated value will lead to economic incentives for landowners to cut back invasive Acacia spp. more frequently, thus reducing excess biomass, which exacerbates wildfire risk.
High-cyclic polycyclic aromatic hydrocarbons (PAHs), with complex fused aromatic structures, are widespread, refractory and harmful in soil, but the current remediation technologies for high-cyclic ...PAHs are often inefficient and costly. This study focused on the biodegradation process of high-cyclic benzoapyrene by Trametes versicolor crude enzymes. The crude enzymes exhibited high laccase activity (22112 U/L) and benzoapyrene degradation efficiency (42.21%) within a short reaction time. Through the actual degradation and degradation kinetics, the degradation efficiency of PAHs decreased with the increase of aromatic rings. And the degradation conditions (temperature, pH, Cu
2+
concentration, mediator) were systematically optimised. The optimum degradation conditions (1.5 mM Cu
2+
, 28℃ and pH 6) showed significant degradation efficiency for the low and medium concentrations of benzoapyrene. In addition, complete degradation of benzoapyrene could be achieved using only 0.2 mM of HBT mediator compared with crude enzymes alone. Collectively, these results showed the high-cyclic PAHs degradation potential of Trametes versicolor crude enzymes, and provided references to evaluate applicable prospects of white rot fungus crude enzymes in PAHs-contaminated soils.
Environmental bisphenol F (BPF) has a cyclic endocrine disruption effect, seriously threatening animal and human health. It is frequently detected in environmental samples worldwide. For BPF ...remediation, biological methods are more environmentally friendly than physicochemical methods. White-rot fungi have been increasingly studied due to their potential capability to degrade environmental pollutants.
Phanerochaete sordida
YK-624 has been shown to degrade BPF by ligninolytic enzymes under ligninolytic conditions. In the present study, degradation of BPF under non-ligninolytic conditions (no production of ligninolytic enzymes) was investigated. Our results showed that BPF could be completely removed after 7-d incubation. A metabolite of BPF, 4,4’-dihydroxybenzophenone (DHBP) was identified by mass spectrometry and nuclear magnetic resonance, and DHBP was further degraded by this fungus to form 4-hydroxyphenyl 4-hydroxybenzoate (HPHB). DHBP and HPHB were the intermediate metabolites of BPF and would be further degraded by
P. sordida
YK-624. We also found that cytochrome P450s played an important role in BPF degradation. Additionally, transcriptomic analysis further supported the involvement of these enzymes in the action of BPF degradation. Therefore, BPF is transformed to DHBP and then to HPHB likely oxidized by cytochrome P450s in
P. sordida
YK-624. Furthermore, the toxicological studies demonstrated that the order of endocrine-disrupting activity for BPF and its metabolites was HPHB > BPF > DHBP.
Key points
• White-rot fungus Phanerochaete sordida YK-624 could degrade BPF.
• Cytochrome P450s were involved in the BPF degradation.
• The order of endocrine disrupting activity was: HPHB > BPF > DHBP.
Graphical abstract
White-rot basidiomycete fungi are a unique group of organisms that evolved an unprecedented arsenal of extracellular enzymes for an efficient degradation of all components of wood such as cellulose, ...hemicelluloses and lignin. The exoproteomes of white-rot fungi represent a natural enzymatic toolbox for white biotechnology. Currently, only exoproteomes of a narrow taxonomic group of white-rot fungi—fungi belonging to the Polyporales order—are extensively studied. In this article, two white-rot fungi, Peniophora lycii LE-BIN 2142 from the Russulales order and Trametes hirsuta LE-BIN 072 from the Polyporales order, were compared and contrasted in terms of their enzymatic machinery used for degradation of different types of wood substrates—alder, birch and pine sawdust. Our findings suggested that the studied fungi use extremely different enzymatic systems for the degradation of carbohydrates and lignin. While T. hirsuta LE-BIN 072 behaved as a typical white-rot fungus, P. lycii LE-BIN 2142 demonstrated substantial peculiarities. Instead of using cellulolytic and hemicellulolytic hydrolytic enzymes, P. lycii LE-BIN 2142 primarily relies on oxidative polysaccharide-degrading enzymes such as LPMO and GMC oxidoreductase. Moreover, exoproteomes of P. lycii LE-BIN 2142 completely lacked ligninolytic peroxidases, a well-known marker of white-rot fungi, but instead contained several laccase isozymes and previously uncharacterized FAD-binding domain-containing proteins.
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