Phanerochaete Research Articles

Comparative Analysis on Microwave and Pressure Cooker Pre-Treatment of Lignocellulosic Biomass in Glucose Production via Fungal Treatment

Oil Palm Empty Fruit Bunch (OPEFB) is lignocellulosic biomass waste generated from palm oil processing industries. Due to its significant compositions of cellulose, hemicellulose, and lignin, OPEFB can be further utilized and converted into value-added chemical products which can be used as alternative energy. Hence, the focus of this research is to analyze the effect of microwave pre-treatment (MP) and pressure cooker pre-treatment (PCP) parameters on OPEFB lignin reduction. The treated OPEFB was directly processed using two serial fungal treatment processes. The first fungal treatment process (FT-1) was to maximize the OPEFB lignin removal while the second fungal treatment process (FT-2) was to maximize the glucose production. Combination of microbes such as Phanerochaete chrysosporium, Trichoderma harzianum, Aspergillus niger, and Tricodherma viride was used for both fungal treatment processes. The OPEFB passing 25-mesh screening was used as raw materials. The raw materials mixed with 0.05 w/w NaOH pellets and water to achieve a concentration ratio of 3/50 (w/v) were pre-treated with either MP or PCP. Subsequently, the slurry produced from the pre-treatment process was introduced to FT-1 (P. chrysosporium for 5 days) and finally to FT-2 (T. harzianum, A. niger and T. viride for 4 days). The compositions of lignin, cellulose, hemicellulose, and glucose were analyzed at each process transition and the end of the whole process. It was observed that PCP (60 mins) was the best pre-treatment process with 39.23%-w of lignin removed. On the other hand, combination of MP (150 watts, 60 mins) was followed with FT-1 removed 66.67%-w of lignin. Only around 38.37%-w of lignin was removed when using the whole process, e.g., MP (150 watts, 60 mins), FT-1, and FT-2. The highest composition of glucose, ca. 131.02%-w, was obtained when 40-min PCP followed with FT-1 and FT-2 was applied. The obtained results exhibited that large lignin removal did not necessarily promote high glucose yield in the final product as observed in the 60-min PCP, e.g., P. chrysosporium consumed not only lignin but also presumably hemicellulose and cellulose.

Heterologously Expressed Cellobiose Dehydrogenase Acts as Efficient Electron-Donor of Lytic Polysaccharide Monooxygenase for Cellulose Degradation in Trichoderma reesei.

The conversion of lignocellulosic biomass to second-generation biofuels through enzymes is achieved at a high cost. Filamentous fungi through a combination of oxidative enzymes can easily disintegrate the glycosidic bonds of cellulose. The combination of cellobiose dehydrogenase (CDH) with lytic polysaccharide monooxygenases (LPMOs) enhances cellulose degradation in many folds. CDH increases cellulose deconstruction via coupling the oxidation of cellobiose to the reductive activation of LPMOs by catalyzing the addition of oxygen to C-H bonds of the glycosidic linkages. Fungal LPMOs show different regio-selectivity (C1 or C4) and result in oxidized products through modifications at reducing as well as nonreducing ends of the respective glucan chain. T. reesei LPMOs have shown great potential for oxidative cleavage of cellobiose at C1 and C4 glucan bonds, therefore, the incorporation of heterologous CDH further increases its potential for biofuel production for industrial purposes at a reduced cost. We introduced CDH of Phanerochaete chrysosporium (PcCDH) in Trichoderma reesei (which originally lacked CDH). We purified CDH through affinity chromatography and analyzed its enzymatic activity, electron-donating ability to LPMO, and the synergistic effect of LPMO and CDH on cellulose deconstruction. The optimum temperature of the recombinant PcCDH was found to be 45 °C and the optimum pH of PcCDH was observed as 4.5. PcCDH has high cello-oligosaccharide kcat, Km, and kcat/Km values. The synergistic effect of LPMO and cellulase significantly improved the degradation efficiency of phosphoric acid swollen cellulose (PASC) when CDH was used as the electron donor. We also found that LPMO undergoes auto-oxidative inactivation, and when PcCDH is used an electron donor has the function of a C1-type LPMO electron donor without additional substrate increments. This work provides novel insights into finding stable electron donors for LPMOs and paves the way forward in discovering efficient CDHs for enhanced cellulose degradation.

Evaluation Nutrient of Larvae Black Soldier Fly (Hermetia Illucens) on Fermented Palm Oil Sludge Culture Media

Livestock business is affected by 50-70% of feed ingredients. Therefore it needs to find alternative feed ingredients either high nutrient or low cost. This study aims to examine the effect of palm oil sludge fermentation media with different types of fungi and dosage for maintan larvae black soldier fly. The method used in this study was an experimental method by Completely Randomized Factorial Design with 3 replications with 2 factors. Factor A is the type of fungi used with the three treatments and factor B is the dose used with the three treatments. Factor A was the type of fungi used: A1 (Pleurotus ostreatus), A2 (Lentinus edodes) and A3 (Phanerochaete chrysosporium). Factor B is the dose of fungi used: B1 (5%), B2 (7%) and B3 (9%). The variables observed consisted of protein content (%), fat content (%), crude fiber content (%). The mathematical model used is analysis of variance and if there are differences between treatments it is continued with the Duncan’s Multiple Range Test. The results showed that there were interactions with respect to the type of fungi used, crude protein, crude fat and crude fiber. The conclusion from this study is that palm oil sludge fermentation using the type of Lentinus edodes fungi at a dose of 7% can increase crude protein, reduce crude fiber and reduce crude fat of black soldier fly (BSF) larvae.

Assessment of Modified Culture Conditions for Fungal Bio-Oxidation of Sulfidic Gold Ores Performed at Circumneutral pH

The significant neutralization of waste streams required after the acidic bio-oxidation of sulfidic gold ores could be avoided by performing a novel treatment at circumneutral pH with an in situ neutralization. For the first time, the white-rot fungus Phanerochaete chrysosporium was incubated in a modified culture medium containing corn steep, an industrial waste product, to support microbial activity and, subsequently, the oxidation of a sulfidic ore at an initial circumneutral pH environment. In this investigation, the concentration of the native culture medium ingredients was first evaluated with response surface methodology to attain maximum sulfide oxidation. The statistical analysis proposed a modified culture medium composed of 12.86 g/L glucose, 2.20 g/L malt extract, 1.67 g/L yeast extract, and 0.49 g/L MgSO4·7H2O to reach a maximum of 28.7% sulfide oxidation after 14 d-bio-oxidation. pH-controlled batch cultures showed that an increase in initial pH in the range of 5.8 to 7.0 reduced the microbial activity, affecting sulfide oxidation. In addition, the modified culture medium at which yeast extract was substituted with 1.67 g/L corn steep produced comparable microbial activity and sulfide oxidation after 14 d, attaining 21.6% at 5% w/v with a maximum 39 U/L lignin peroxidase and 116 U/L manganese peroxidase. A 40.6% sulfide oxidation and 43.8% gold recovery were obtained after 42 d three-cycle replenishing bio-oxidation and 24 h cyanidation, respectively. Overall, corn steep waste showed the potential to substitute more expensive culture medium ingredients, supporting microbial activity and oxidation of sulfidic gold ores at an initial circumneutral pH and contributing to circularity of waste management.

Preparing the pure lignin peroxidase and exploring the effects of chemicals on the activity

Heterogous expression of lignin peroxidase (LiP) from Phanerochaete chrysosporium was performed in by E. coli prokaryotic expression system, and pure LiP was prepared by washing, refolding, and purification. The enzyme activity was measured by the resveratrol oxidation method. The effects of different chemicals on LiP activity were explored by adding different kinds of metal ions, acids/phenols, and surfactants. The optimal pH and temperature are 4.2 and 40 °C. The single-factor screening experiment showed that adding 1 mM Mn2+, 0.1 mM DL-lactic acid, and 2% PEG-4000 had the best promotion effect on the enzyme activity of recombinant LiP, which was 160.61%, 188.46%, and 247.83%, respectively. Further, the synergistic addition of Mn2+ and PEG-4000 achieved the best enzyme activity promotion effect of 277.51%. In addition, the addition of DL-lactic acid alone could promote LiP activity. However, the co-addition of lactic acid with Mn2+ and PEG-4000 contributed only 247.87%, which indicated that the addition of DL-lactic acid had an inhibitory effect when applied synergistically. For the first time, it was found that PEG-4000 increased LiP enzyme activity obviously and had a synergistic effect with Mn2+, serving as a reference for LiP in studies and applications pertaining to lignin breakdown.

Removal of perfluorooctanoic acid (PFOA) in the liquid culture of Phanerochaete chrysosporium

Perfluorooctanoic acid (PFOA) is becoming a concern due to its persistence, bioaccumulation, and potential harmful effects on humans and the environment. In this study, the fungus Phanerochaete chrysosporium (P. chrysosporium) was used to remove the PFOA in liquid culture system. The results showed that the average activities of laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP) enzymes secreted by P. chrysosporium were 0.0003 U/mL, 0.013 U/mL, and 0.0059 U/mL, respectively, during the incubation times of 0–75 days. The pH of 3 and incubation time of 45–55 days were the optimum parameters for the three enzymes activities. The enzyme activities in P. chrysosporium incubation system were firstly inhibited by adding PFOA and then they were enhanced after 14 days. The maximum removal efficiency of PFOA (69.23%) was achieved after 35 days in P. chrysosporium incubation system with an initial PFOA concentration of 0.002 mM and no veratryl alcohol (VA). Adsorption was not a main pathway for PFOA removal and the PFOA adsorbed in fungi mycelial mat accounted for merely 1.91%. The possible products of PFOA contained partially fluorinated aldehyde, alcohol, and aromatic ring. These partially fluorinated compounds might result from PFOA degradation via a combination of cross-coupling and rearrangement of free radicals.

Investigating the Potential of Fusarium solani and Phanerochaete chrysosporium in the Removal of 2,4,6-TNT.

Past and recent applications of 2,4,6-trinitrotoluene (TNT) in military and civilian industries have led to contamination of soil and marine ecosystems. Among various TNT remediation techniques, biological remediation is widely accepted for its sustainability, low cost, and scalable applications. This study was designed to isolate a fungus strain from a TNT-contaminated soil to investigate its tolerance to and potential for removal of TNT. Thus, a soil column with a history of periodic TNT amendment was used to isolate dominant strains of fungi Fusarium solani isolate, which is not commonly reported for TNT mineralization and was found predominant in the subsurface layer of the TNT-amended soil. F. solani was investigated for TNT concentration tolerance at 30, 70, and 100mg/L on agar plates and for TNT removal in liquid cultures at the same given concentrations. F. solani activity was compared with that of a reference soil-born fungus that has been intensively studied for TNT removal (Phanerochaete chrysosporium) obtained from the American Type Culture Collection. On agar media, F. solani showed a larger colony diameter than P. chrysosporium at similar TNT concentrations, indicating its high potential to tolerate toxic levels of TNT as found in contaminated sites. In the liquid culture medium, F. solani was able to significantly produce higher biomass than P. chrysosporium in all TNT concentrations. The TNT removal percentage from the liquid culture at the highest TNT concentration of 100mg/L reached about 85% with F. solani, while P. chrysosporium was no better than 25% at the end of an 84-h incubation period. Results indicate a significant potential of using F. solani in the bioremediation of polluted TNT soils that overcome the high concentration barrier in the field. However, further investigation is needed to identify enzymatic potential and the most effective applications and possible limitations of this method on a large scale.

Fungus reduces tetracycline-resistant genes in manure treatment by predation of bacteria

New strategies to remove antibiotic resistance genes (ARGs), one of the most pressing threats to public health, are urgently needed. This study showed that the fungus Phanerochaete chrysosporium seeded to a composting reactor (CR) could remarkably reduce tetracycline-resistant genes (TRGs). The reduction efficiencies for the five main TRGs (i.e., tetW, tetO, tetM, tetPA, and tet(32)) increased by 8 to 100 folds compared with the control without P. chrysosporium, and this could be attributed to the decrease in the quantity of bacteria. Enumeration based on green fluorescence protein labeling further showed that P. chrysosporium became dominant in the CR. Meanwhile, the bacteria in the CR invaded the fungal cells via the cell wall defect of chlamydospore or active invasion. Most of the invasive bacteria trapped inside the fungus could not survive, resulting in bacterial death and the degradation of their TRGs by the fungal nucleases. As such, the predation of tetracycline-resistant bacteria by P. chrysosporium was mainly responsible for the enhanced removal of TRGs in the swine manure treatment. This study offers new insights into the microbial control of ARGs.

Biodegradation of Benzo[a]pyrene by a White-Rot Fungus Phlebia acerina: Surfactant-Enhanced Degradation and Possible Genes Involved.

Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental pollutants that pose a threat to human health. Among these PAHs, benzo[a]pyrene (BaP), a five-ring compound, exhibits high resistance to biodegradation. White-rot fungus Phlebia acerina S-LWZ20190614-6 has demonstrated higher BaP degradation capabilities compared with Phanerochaete chrysosporium and P. sordida YK-624, achieving a degradation rate of 57.7% after 32 days of incubation under a ligninolytic condition. To further enhance the biodegradation rate, three nonionic surfactants were used, and the addition of 1 or 2 g·L-1 of polyethylene glycol monododecyl ether (Brij 30) resulted in nearly complete BaP biodegradation by P. acerina S-LWZ20190614-6. Interestingly, Brij 30 did not significantly affect the activity of manganese peroxidase and lignin peroxidase, but it did decrease laccase activity. Furthermore, the impact of cytochrome P450 on BaP degradation by P. acerina S-LWZ20190614-6 was found to be relatively mild. Transcriptomic analysis provided insights into the degradation mechanism of BaP, revealing the involvement of genes related to energy production and the synthesis of active enzymes crucial for BaP degradation. The addition of Brij 30 significantly upregulated various transferase and binding protein genes in P. acerina S-LWZ20190614-6. Hence, the bioremediation potential of BaP by the white-rot fungus P. acerina S-LWZ20190614-6 holds promise and warrants further exploration.

Degradation of co-applied Atrazine and Fipronil in Phanerochaete Chrysosporium Augmented Biobeds.

White rot fungi possess an enzymatic system that is non-specific to any pesticide and can be used for pesticide detoxification in biobeds. The present study evaluated potential of Phanerochaete chrysosporium to degrade co-applied atrazine and fipronil in ash or biochar biomixtures. Five biomixtures were prepared by partially replacing compost in rice straw-compost biomixture (BM) with 10% rice husk ash (RHA), 10% sugarcane bagasse ash (SBA), and 1 and 5% wheat straw biochar (WBC). Results suggested that after 30 days P. chrysosporium augmented biobeds resulted in 60.52-72.72% atrazine and 69.57-72.52% fipronil degradation. Hydroxyatrazine and fipronil sulfone were detected as the only metabolite of atrazine and fipronil, respectively, and were further degraded. Although, SBA significantly enhanced atrazine degradation, RHA or SBA had no significant effect on fipronil degradation. WBC (5%) slowed down degradation of both pesticides.

Mitigation of soil N2O emissions by decomposed straw based on changes in dissolved organic matter and denitrifying bacteria

The return of decomposed straw represents a less explored potential option for reducing N2O emissions. However, the mechanisms underlying the effects of decomposed straw return on soil N2O mitigation are still not fully clear. Therefore, we used a helium atmosphere robotized continuous flow incubation system to compare the soil N2O and N2 emissions from four treatments: CK (control: no straw), WS (wheat straw), IWS (wheat straw decomposed with Irpex lacteus), and PWS (wheat straw decomposed with Phanerochaete chrysosporium). All the treatments have been fertilized with the same amount of KNO3. Furthermore, we also analyzed i) the chemodiversity of soil dissolved organic matter (DOM), ii) the nirS, nirK, and nosZ gene copies and relative abundances of denitrifying bacterial communities (DBCs), and iii) the specific linkages between N2O emissions and DOM and DBC. The results showed that the WS, IWS and PWS treatments increased N2O emissions compared to the CK treatment. However, applying decomposed straw to soil, especially straw treated with P. chrysosporium, effectively decreased the soil N2O and increased N2 emissions compared to WS and IWS. Moreover, the IWS and PWS treatments increased the CHO composition, but they decreased the CHON and CHOS compositions of heteroatomic compounds of DOM compared with the WS and CK treatments. Furthermore, the WS, IWS and PWS treatments all significantly increased the nirS and nosZ gene copies compared with the CK treatment. Additionally, compared with the other treatments, the PWS treatment significantly shaped the DBC and led to a higher relative abundance of Pseudomonas with nirS and nosZ genes. Meanwhile, Network analysis showed that the mitigation of N2O was closely related to particular DOM molecules, and specific DBC taxa. These results highlight the potential for decomposed straw amendments to mitigate of soil N2O emissions not only by changing soil DOM but also mediating the soil DBC.

Effect of the inoculation of Phanerochaete chrysosporium on nitrogen migration and organic matter conversion during electrolytic manganese residue composting

Composting has made it practicable to dispose electrolytic manganese residues (EMR) in a less toxic way, nevertheless, the decomposition and the loss of nitrogen is a critical issue. This study aimed to investigate the role of Phanerochaete chrysosporium (PC) inoculation on nitrogen migration and promotion of decomposing organic matter (OM), as well as the effect on bacterial community structure during EMR composting. The results exhibited that nitrogen loss tallied with the first-order kinetic model. PC inoculation increased the relative microbial abundance of Firmicutes, which improved the efficiency of nitrogen nitrification and OM degradation, and increased the germination index and total nitrogen content by 13.8% and 2.95 g/kg, respectively. Moreover, aromatic benzenes replaced heteropolysaccharides, alcohols and ethers as the main components of OM in fertilizer, leading up to a more stable humus structure. This study provides a rationale and a novel perspective on the resource and nutrient conservation of EMR-contaminated soils.

Systematic exploration of the interactions between anionic polyacrylamide and manganese peroxidase based on docking and molecular dynamics simulations

The biodegradation of anionic polyacrylamide (HPAM) mediated by manganese peroxidase (Mn P) has been experimentally discovered and reported by researchers, but the interaction mechanism of Mn P with HPAM at molecular level is still unclear. Here, the molecular mechanisms of HPAM structure models with Mn P obtained from Phanerochaete chrysosporium were investigated by docking and molecular dynamics (MD) simulations. The results indicate that both the number of H-bonds formed and key residues in MnP-HPAM-5 are the largest, leading to its maximal binding affinity. HPAM models contact with an active site of Mn P by H-bonds and hydrophobic interactions to maintain their stability. The binding of HPAM-5 results in the significant change and unfolding of enzyme structure, and the thicker hydration shell produced by a large amount of water molecule near the enzyme surface and the binding region makes HPAM-5 difficult to access the active site of enzyme. The enzyme structure is the most stable when it binds to HPAM-4, and the higher water molecules may form H-bonds with its binding region. These facilitate mass transfer, beneficial to its binding. This study provides the theoretical reference for designing the enzyme with higher activity and stability to enhance the degradation performance of HPAM.

Elucidating the role of media nitrogen in augmenting the production of lignin-depolymerizing enzymes by white-rot fungi.

Indigenous white-rot fungal isolates Schizophyllum commune, Phanerochaete chrysosporium, Ganoderma racenaceum, and Lentinus squarrosulus, demonstrating the ability to depolymerize lignin of the crop residues, were studied for their potential to produce ligninolytic enzymes using modified production media under conditions of limiting and excess nitrogen for higher enzymatic expressions. Secretome-rich media on the investigation confirmed the successful production of lignin-depolymerizing enzymes, viz. laccase, lignin peroxidase, manganese peroxidase, and versatile peroxidase. Production of laccases and peroxidases was statistically significant in nitrogen-limiting media with and without the substrate, across all white-rot fungal cultures at 95% confidence interval. Nitrogen-limiting media with the substrate on analysis extracellularly expressed 99.27 U of laccase and 68.48 U of manganese peroxidase in Schizophyllum commune, while 195.14 U of lignin peroxidase was produced by Phanerochaete chrysosporium. Lentinus squarrosulus expressed 455.34 U of laccase and 357.13 U of versatile peroxidase with 250.09 U of laccase and 206.95 U of manganese peroxidase produced by Ganoderma racenaceum for every milliliter of the media used. Nitrogen-limiting media triggered the production of laccase during the initial stages of growth while the expression of peroxidases was predominant at a later stage. Also, this media evinced increased enzymatic yields with low biomass content compared to nitrogen-excess conditions. The extant study confirmed the positive influence of nitrogen-limiting media in the efficient production of ligninolytic enzymes and their suggestive degradation potential for environmental pollutants, making these enzymes a safe, clean alternative to the use of chemicals and the media to be effective for large-scale production of ligninolytic enzymes. IMPORTANCE Lignin on account of its high abundance, complex polymeric structure, and biochemical properties is identified as a promising candidate in renewable energy and bioproduct manufacturing. However, depolymerization of lignin remains a major challenge in lignin utilization, entailing the employment of harsh treatments representing not only an environmental concern but also a waste of economic potential. Developing an alternative green technology to minimize this impact is imperative. Methods using enzymes to depolymerize lignin are the focus of recent studies. Current research work emphasized the efficient expression of the major lignin-depolymerizing enzymes: laccases, lignin peroxidases, manganese peroxidases, and versatile peroxidases from native isolates of white-rot fungus for several biotechnological applications as well as treatment of crop residues for use as ruminant feed in improving productivity. The importance of nitrogen in augmenting the expression of lignin-depolymerizing enzymes and providing a media recipe for the cost-effective production of ligninolytic enzymes is highlighted.

Synergistic lignin degradation between Phanerochaete chrysosporium and Fenton chemistry is mediated through iron cycling and ligninolytic enzyme induction.

Removal of recalcitrant lignin from wastewater remains a critical bottleneck in multiple aspects relating to microbial carbon cycling ranging from incomplete treatment of biosolids during wastewater treatment to limited conversion of biomass feedstock to biofuels. Based on previous studies showing that the white rot fungus Phanerochaete chrysosporium and Fenton chemistry synergistically degrade lignin, we sought to determine optimum levels of Fenton addition and the mechanisms underlying this synergy. We tested the extent of degradation of lignin under different ratios of Fenton reagents and found that relatively low levels of H2O2 and Fe(II) enhanced fungal lignin degradation, achieving 80.4 ± 1.61 % lignin degradation at 1.5 mM H2O2 and 0.3 mM Fe(II). Using a combination of whole-transcriptome sequencing and iron speciation assays, we determined that at these concentrations, Fenton chemistry induced the upregulation of 80 differentially expressed genes in P. ch including several oxidative enzymes. This study underlines the importance of non-canonical, auxiliary lignin-degrading pathways in the synergy between white rot fungi and Fenton chemistry in lignin degradation. We also found that, relative to the abiotic control, P. ch. increases the availability of Fe(II) for the production of hydroxyl radicals in the Fenton reaction by recycling Fe(III) (p < 0.001), decreasing the Fe(II) inputs necessary for lignin degradation via the Fenton reaction.

Harvesting Mycelial Biomass of Selected Basidiomycetes for Chitosan Biopolymer Extraction.

This study investigates the mycelial biomass production and chitosan extraction potential of various Basidiomycota strains, including Heterobasidion annosum, Phanerochaete chrysosporium, Pleurotus ostreatus, Trametes versicolor, and Lentinus lepideus. Both submerged fermentation (SF) and solid-state fermentation (SSF) methods were employed. The chitosan yield in basidiocarps of Pleurotus ostreatus, Agaricus bisporus, and Ganoderma applanatum was also evaluated as a reference material. The chitosan extracted from fungal cells was characterized using elemental analyses and FTIR spectroscopy. Among the cultivated strains, P. chrysosporium exhibited the highest mycelial biomass concentration in SF (1.03 g 100 mL-1) after 14 days, while T. versicolor achieved the highest biomass concentration in SSF (3.65 g 100 mL-1). The highest chitosan yield was obtained from the mycelium of P. chrysosporium (0.38%) and T. versicolor (0.37%) in shaken SF. Additionally, commercially cultivated A. bisporus demonstrated the highest chitosan yield in fungal fruiting bodies (1.7%). The extracted chitosan holds potential as a functional biopolymer additive for eco-friendly materials, serving as an alternative to synthetic wet and dry strength agents in packaging materials.

Comparative Genomics and Transcriptomics Analyses Reveal Divergent Plant Biomass-Degrading Strategies in Fungi.

Plant biomass is one of the most abundant renewable carbon sources, which holds great potential for replacing current fossil-based production of fuels and chemicals. In nature, fungi can efficiently degrade plant polysaccharides by secreting a broad range of carbohydrate-active enzymes (CAZymes), such as cellulases, hemicellulases, and pectinases. Due to the crucial role of plant biomass-degrading (PBD) CAZymes in fungal growth and related biotechnology applications, investigation of their genomic diversity and transcriptional dynamics has attracted increasing attention. In this project, we systematically compared the genome content of PBD CAZymes in six taxonomically distant species, Aspergillus niger, Aspergillus nidulans, Penicillium subrubescens, Trichoderma reesei, Phanerochaete chrysosporium, and Dichomitus squalens, as well as their transcriptome profiles during growth on nine monosaccharides. Considerable genomic variation and remarkable transcriptomic diversity of CAZymes were identified, implying the preferred carbon source of these fungi and their different methods of transcription regulation. In addition, the specific carbon utilization ability inferred from genomics and transcriptomics was compared with fungal growth profiles on corresponding sugars, to improve our understanding of the conversion process. This study enhances our understanding of genomic and transcriptomic diversity of fungal plant polysaccharide-degrading enzymes and provides new insights into designing enzyme mixtures and metabolic engineering of fungi for related industrial applications.

A novel combinatorial approach for cleaner production of biodegradable sheets from the combination of paddy straw and pine needle waste

The study aims at providing a cleaner technology by employing a combinatorial approach of mild chemical treatment of 1% Ca(OH)2 followed by Phanerochaete chrysosporium, (laccase producer) on paddy straw and pine needles in combination, for getting cellulose-rich pulp for making biodegradable paper sheets. Response surface methodology was adopted by choosing two response parameters – cellulose content and residual lignin content after pulping to optimize the cooking conditions. The pulp derived after optimizing the parameters i.e., solid: liquid ratio (1:7), temperature (160 °C), time of digestion (60 min), and NaOH concentration (4%) was characterized. SEM and FTIR analysis, showed a more condensed cellulose network and –OH bonds when compared with alpha-cellulose. Best pulp (kappa no. 24 and ֯SR 59) was casted to produce biodegradable paper sheets of different GSM types (40, 50, 75, 100 GSM), and their different mechanical properties were tested. The maximum tensile strength (110 Nm/g) and Cobb index (345.77 g/m2) were seen in 100 GSM sheets which is comparable with regular corrugated sheets.

Microbial pretreatment of camelina straw and switchgrass by Trametes versicolor and Phanerochaete chrysosporium to improve physical quality and enhance enzymatic digestibility of solid biofuel pellets

In this study, optimization of solid-state fermentation of Camelina sativa residues (camelina straw, CS) and Panicum virgatum (switchgrass, SG) by Trametes versicolor 52J (TV52J), Trametes versicolor m4D (TVm4D), and Phanerochaete chrysosporium (PC) was conducted. At optimal conditions, the tensile strength, unit density and mass loss for CS pellets were 6.2 MPa, 1139 kg m−3, and 33%, respectively after 31 d pretreatment by TVm4D, while for SG pellets, they were 1.6 MPa, 1244 kg m−3 , and 13.8%, respectively after 32 d pretreatment by TVm4D. Although the holocellulose content of microbially pretreated CS and SG pellets dropped from 58.6 to 36.7%, and from 66.2 to 46.3%, respectively, the glucose yield of CS pellets increased from 12.9 to 61.1% with a corresponding xylose yield increase from 14.7 to 60.1%. The glucose and xylose yield of SG increased from 10.9 to 59.9% and 13.4 to 35.7%, respectively. It can be concluded that microbial pretreatment contributed to mass loss of the samples but trivially affected the energy content and significantly boosted the physical properties and enzymatic digestibility of the treated pellets. The microbially pretreated CS is recommended for densification and combustion while the microbially pretreated SG is more suitable for biochemical conversion.

Application of Phanerochaete chrysosporium for enhancing gold recovery via bio-oxidation of refractory sulfidic ores in a circumneutral environment

Regardless of the effectiveness of the industrial process design for gold recovery encompassing acidic bio-oxidation and cyanidation, the substantial neutralization of effluents required after bio-oxidation results in a considerable generation of waste streams. Conducting a bio-oxidation at circumneutral pH with in-situ neutralization is a novel technological opportunity for strengthening environmental protection and safety. For the first time, this research reports the capacity of Phanerochaete chrysosporium to oxidize a low-grade refractory gold ore at circumneutral pH. The fungal treatment was evaluated in five culture media regarding pH variation, enzyme activity, and sulfide oxidation. Thereafter, optimal conditions were investigated and then scaled up in a bioreactor. Results indicated that pH > 5.0 decreased the enzyme concentration released by P. chrysosporium, reducing sulfide oxidation. An initial pH of 5.8 led to a 24.4 ± 2.2% sulfide oxidation after 14 days, comparatively better to reported studies in the same pH range. A higher efficiency was attained by replenishing the fungal culture for three cycles, reaching 47.6 ± 2.3% sulfide oxidation and 49.5 ± 2.4% gold recovery. The results were confirmed by UV–visible, C/S detector, SEM and gold fire assay. Overall, this study opens a possibility to explore a bio-oxidation at higher pH, contributing to the vision of a net-zero target.