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Abstract Inonotus obliquus is a pathogenic fungus found in living trees and has been widely used as a traditional medicine for cancer therapy. Although lignocellulose-degrading enzymes are involved in the early stages of host infection, the parasitic life cycle of this fungus has not been fully understood. In this study, we aimed to investigate the activities of laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP) from I. obliquus cultivated in Kirk’s medium. The fungus was subjected to genome sequencing, and genes related to wood degradation were identified. The draft genome sequence of this fungus comprised 21,203 predicted protein-coding genes, of which 134 were estimated to be related to wood degradation. Among these, 47 genes associated with lignin degradation were found to have the highest number of mnp genes. Furthermore, we cloned the cDNA encoding a putative MnP, referred to as IoMnP1, and characterized its molecular structure. The results show that IoMnP1 has catalytic properties analogous to MnP. Phylogenetic analysis also confirmed that IoMnP1 was closely related to the MnPs from Pyrrhoderma noxium, Fomitiporia mediterranea, and Sanghuangporus baumii, which belong to the same family of Hymenochaetaceae. From the above results, we suggest that IoMnP1 is a member of MnPs.

White Rot Fungi (WRF) are a class of microorganisms widely understood for their ability to breakdown an extensive range of pollutants generally found in industrial wastewater. This specific literature review centers on the abilities of the White Rot Fungi to treat industrial wastewater, analysis of the biodegradation mechanism, future applications, and scaling up for practical implementation. WRF usually carry out the degradation process with ligninolytic enzyme by targeting complex industrial pollutants, such as aromatic hydrocarbons, dyes, pharmaceuticals, and products of personal care. The unique enzymatic system of WRF converts the complex and harmful industrial pollutants into harmless end and byproducts, thus minimizing the impact on the environment and ecosystem. This review paper also discusses the potential applications of WRF, such as bioremediation, biosorption, and co-culturing with bacteria to enhance the pollutants removal efficiency of already functional wastewater treatment plants. However, there are still challenges in scaling up WRF-based treatment facilities due to factors such as the optimization of conditions and processes of already functional conventional wastewater treatment plants, cost effectiveness, and design modifications of treatment facilities. Conclusively, WRF fungi can play an important role in degrading complex organic and inorganic pollutants specifically, which are not usually treated by conventional wastewater treatment plants. [ABSTRACT FROM AUTHOR]

Inonotus obliquus is a pathogenic fungus found in living trees and has been widely used as a traditional medicine for cancer therapy. Although lignocellulose-degrading enzymes are involved in the early stages of host infection, the parasitic life cycle of this fungus has not been fully understood. In this study, we aimed to investigate the activities of laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP) from I. obliquus cultivated in Kirk's medium. The fungus was subjected to genome sequencing, and genes related to wood degradation were identified. The draft genome sequence of this fungus comprised 21,203 predicted protein-coding genes, of which 134 were estimated to be related to wood degradation. Among these, 47 genes associated with lignin degradation were found to have the highest number of mnp genes. Furthermore, we cloned the cDNA encoding a putative MnP, referred to as IoMnP1, and characterized its molecular structure. The results show that IoMnP1 has catalytic properties analogous to MnP. Phylogenetic analysis also confirmed that IoMnP1 was closely related to the MnPs from Pyrrhoderma noxium, Fomitiporia mediterranea, and Sanghuangporus baumii, which belong to the same family of Hymenochaetaceae. From the above results, we suggest that IoMnP1 is a member of MnPs. [ABSTRACT FROM AUTHOR]

White Rot Fungi (WRF) are a class of microorganisms widely understood for their ability to breakdown an extensive range of pollutants generally found in industrial wastewater. This specific literature review centers on the abilities of the White Rot Fungi to treat industrial wastewater, analysis of the biodegradation mechanism, future applications, and scaling up for practical implementation. WRF usually carry out the degradation process with ligninolytic enzyme by targeting complex industrial pollutants, such as aromatic hydrocarbons, dyes, pharmaceuticals, and products of personal care. The unique enzymatic system of WRF converts the complex and harmful industrial pollutants into harmless end and byproducts, thus minimizing the impact on the environment and ecosystem. This review paper also discusses the potential applications of WRF, such as bioremediation, biosorption, and co-culturing with bacteria to enhance the pollutants removal efficiency of already functional wastewater treatment plants. However, there are still challenges in scaling up WRF-based treatment facilities due to factors such as the optimization of conditions and processes of already functional conventional wastewater treatment plants, cost effectiveness, and design modifications of treatment facilities. Conclusively, WRF fungi can play an important role in degrading complex organic and inorganic pollutants specifically, which are not usually treated by conventional wastewater treatment plants.

The objective of this study was aiming at developing an efficient strategy to promote enzymatic hydrolysis of naked oat straw and deciphering the potential mechanism. Irpex lacteus and Phlebia acerina were employed to inoculated on the naked oat straw for 4 weeks which the changes of fiber components, fermentation losses, lignin-degrading enzymes production pattern were determined weekly. Furthermore, the 72 h enzymatic hydrolysis of ultimately fermented naked oat straw were also evaluated. The acid detergent lignin was degraded at about 25% along with the moderate dry matter and cellulose loss which both showed selective degradation. The lignin-degrading enzymes production patterns of the two fungi were different which lignin peroxidase was not detected in Irpex lacteus treatment. In addition, the activities of cellulolytic enzymes were higher in Phlebia acerina treatment. After 72 h enzymatic hydrolysis, the reducing sugar content and hydrolysis yield pretreated by Irpex lacteus was 12.92 g/L and 69.49%, respectively. It was much higher than that in sterilized substrate and Phlebia acerina treatment. Meanwhile, the hydrolysis yields of glucose, sum of xylose and arabinose were all improved by Irpex lacteus which were 30.96% and 25.62%, respectively, and showed significant enhancements compared to control and Phlebia acerina treatment. Irpex lacteus is one of effective white rot fungi which could promote the enzymatic hydrolysis of naked oat straw obviously. [ABSTRACT FROM AUTHOR]

C4 grasses are common species in rangelands around the world and represent an attractive option for second-generation biofuel production. Although they display high polysaccharide content and reach great levels of biomass accumulation, there is a major technical issue to be addressed before they can be used for bioethanol industrial production: lignin removal. Concerning this, Pycnoporus and Ganoderma fungal genera have been highlighted due to their ability to hydrolyze lignocellulose in biological pretreatments. Our goals here were to evaluate the pretreatment efficiency using the secretome of species from Pycnoporus and Ganoderma spp. harvested from a glucose-free inductive medium (using a C4 grass) and to identify the fungal enzymatic activities responsible for the lignin degradation and glucose release. Our results show that P. sanguineus secretome exhibits a higher activity of lignocellulolytic enzymes such as cellulases, xylanases, laccases, and manganese peroxidases compared with that from G. resinaceum. Interestingly, zymograms in the presence of 2 M glucose suggest that a β-glucosidase isoform from P. sanguineus could be glucose tolerant. The proteomic approach carried out allowed the identification of 73 and 180 different proteins in G. resinaceum and P. sanguineus secretomes, respectively, which were functionally classified in five main categories and a miscellaneous group. These results open new avenues for future experimental work that lead to a deeper comprehension and a greater application of the mechanisms underlying lignocellulosic biomass degradation. [ABSTRACT FROM AUTHOR]

Lignin is an abundant cell wall component, and it has been used mainly for generating steam and electricity. Nevertheless, lignin valorization, i.e. the conversion of lignin into high value-added fuels, chemicals, or materials, is crucial for the full implementation of cost-effective lignocellulosic biorefineries. From this perspective, rapid screening methods are crucial for time- and resource-efficient development of novel microbial strains and enzymes with applications in the lignin biorefinery. The present review gives an overview of recent developments and applications of a vast arsenal of activity and sequence-based methodologies for uncovering novel microbial strains with ligninolytic potential, novel enzymes for lignin depolymerization and for unraveling the main metabolic routes during growth on lignin. Finally, perspectives on the use of each of the presented methods and their respective advantages and disadvantages are discussed.

Lignin is an abundant cell wall component, and it has been used mainly for generating steam and electricity. Nevertheless, lignin valorization, i.e. the conversion of lignin into high value-added fuels, chemicals, or materials, is crucial for the full implementation of cost-effective lignocellulosic biorefineries. From this perspective, rapid screening methods are crucial for time- and resource-efficient development of novel microbial strains and enzymes with applications in the lignin biorefinery. The present review gives an overview of recent developments and applications of a vast arsenal of activity and sequence-based methodologies for uncovering novel microbial strains with ligninolytic potential, novel enzymes for lignin depolymerization and for unraveling the main metabolic routes during growth on lignin. Finally, perspectives on the use of each of the presented methods and their respective advantages and disadvantages are discussed. [ABSTRACT FROM AUTHOR]

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Overcoming recalcitrance of lignin has motivated bioprospecting of high-yielding enzymes from environmental ligninolytic microorganisms associated with lignocellulose degrading-systems. Here, we performed isolation of 21 ligninolytic strains belonging to the genus Klebsiella spp., driven by the presence of lignin in the media. The fastest-growing strains (FP10-5.23, FP10-5.22 and P3TM1) reached the stationary phase in approximately 24 h, in the media containing lignin as the main carbon source. The strains showed biochemical evidence of ligninolytic potential in liquid- and solid media-converting dyes, which the molecular structures are similar to lignin fragments. In liquid medium, higher levels of dye decolorization was observed for P3TM.1 in the presence of methylene blue, reaching 98% decolorization in 48 h. The highest index values (1.25) were found for isolates P3TM.1 and FP10-5.23, in the presence of toluidine blue. The genomic analysis revealed the presence of more than 20 genes associated with known prokaryotic lignin-degrading systems. Identification of peroxidases (lignin peroxidase—LiP, dye-decolorizing peroxidase—DyP, manganese peroxidase—MnP) and auxiliary activities (AA2, AA3, AA6 and AA10 families) among the genetic repertoire suggest the ability to produce extracellular enzymes able to attack phenolic and non-phenolic lignin structures. Our results suggest that the Klebsiella spp. associated with fresh water and soil may play important role in the cycling of recalcitrant molecules in the Caatinga (desert-like Brazilian biome), and represent a potential source of lignin-degrading enzymes with biotechnological applications. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Lignolytic (lignin degrading) enzyme, from oil palm pathogen Ganoderma boninense Pat. (Syn G. orbiforme (Ryvarden)), is involved in the detoxification and the degradation of lignin in the oil palm and is the rate‐limiting step in the infection process of this fungus. Active inhibition of lignin‐degrading enzymes secreted by G. boninense by various naturally occurring phenolic compounds and estimation of efficiency on pathogen suppression was aimed at. Methods and Results: In our work, 10 naturally occurring phenolic compounds were evaluated for their inhibitory potential towards the lignolytic enzymes of G. boninense. Additionally, the lignin‐degrading enzymes were characterized. Most of the peholic compounds exhibited an uncompetitive inhibition towards the lignin‐degrading enzymes. Benzoic acid was the superior inhibitor to the production of lignin‐degrading enzymes, when compared between the 10 phenolic compounds. The inhibitory potential of the phenolic compounds towards the lignin‐degrading enzymes are higher than that of the conventional metal ion inhibitor. The lignin‐degrading enzymes were stable in a wide range of pH but were sensitive to higher temperature. Conclusion: The study demonstrated the inhibitor potential of 10 naturally occurring phenolic compounds towards the lignin‐degrading enzymes of G. boninense with different efficacies. Significance and Impact of the Study: The study has shed a light towards a new management strategy to control basal stem rot disease in oil palm. It serves as a replacement for the existing chemical control. [ABSTRACT FROM AUTHOR]

In this work, Trichoderma reesei Aq-5b and Trichoderma viride NSW-XM, capable of excreting lignin-degrading enzymes and cellulase were used to create a mixed culture system to hydrolyze rice straw in situ . The results showed that Aq-5b and NSW-XM were able to co-grow and produce complementary lignin degrading enzymes, namely laccase and lignin peroxidase. The two microorganisms were able to produce 22.74 g/L of reducing sugar in the optimal condition. For fermentation of the hydrolysates produced, Saccharomyces cerevisiae and Candida tropicalis NSW-NW were co-immobilized in polymer beads composed of sodium alginate, polyvinyl alcohol, and silicon dioxide (SA–PVA–SiO 2 ). The beads remained intact after 4 cycles of use and provided satisfactory protection for the yeasts and a suitable microenvironment for ethanol fermentation, greatly improved the efficiency of ethanol production, shortened the fermentation cycle and achieved yeasts recycling for continuous or batch-fed fermentation. The productivity of ethanol reached up to 2.17 g/(L h). [ABSTRACT FROM AUTHOR]

Veratryl alcohol (VA) is the main substrate of lignin peroxidase (LiP), a key lignin-degrading enzyme. A redox mediator role, in the lignin degradation process, has been attributed to this molecule; however, many unanswered questions remain about its action mechanism. In this investigation, the basic aspects of a plausible action mechanism, this means VA binding modes to Phanerochaete chrysosporium LiP, were addressed. Docking calculations were used to obtain LiP–VA complexes near to Trp171, the active redox residue where VA is oxidized. Our results show that VA interacts at Trp171 helped by hydrogen bonding interactions with the acidic amino acids Asp264 and Glu168, as well as by hydrophobic interactions with Phe267, confirming previous experimental findings. MM–GBSA calculations, molecular dynamics simulations, and cluster analysis gave further insights into the energetic preferences of the different binding modes and the stability of LiP–VA complexes. A hydrophobic concave ditch, next to Trp171, was observed to stabilize VA at LiP surface, confirming previous suggestions based on the LiP crystal structure. A detailed analysis of the interactions in this site is provided. These findings are expected to be the basis for site-directed mutagenesis and QM/MM experiments that will prove the importance of the identified residues. [ABSTRACT FROM AUTHOR]

Lignin is a common refractory material in the nature, which was abundant and complex, and concealed in crop straw and municipal solid waste. Some bacterial has the function of degrading lignin. This paper took deadwood and dead leaves as the sample, screened C-9 strain by aniline blue plate method, which can degrade lignin and has a higher ability to produce enzymes, so as to attain the high efficient bacteria of lignin-degrading, and provide reference for the stud)' on lignin-degrading by bacterial. It was identified as Arthrobacter sp. through microbial morphology and 16SrDNA. The optimization of enzyme-producing condition for C-9 strain was confirmed by the optimization of enzyme-producing conditions: temperature 30~35°C, rotate speed 150 r/min, culture basis of pH 7~8, the optimal carbon source was starch, the optimal nitrogen source was peptone, and the amount of MnSO4 inducer was 0.8 mmol/L. Under the optimal condition, the lignin peroxidase yield of C-9 strain was 74.62 U/mL, the manganese peroxidase yield of C-9 strain was 58.61 U/mL, and the laccase activity was 68.92 U/mL. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnP-YC4 is a promising yeast consortium for the tolerance of lignin degradation inhibitors. • MnP activity induced by lignin was found to be highly related to dye decolorization by MnP-YC4. • MnP-YC4 demonstrated a strong ability to decolorize the pure sulfonated reactive OII azo dye. • Efficient decolorization of dye-containing simulated and real textile wastewater by MnP-YC4. • Phytotoxicity study revealed the nontoxic nature of the dye metabolites. MnP-YC4, a newly constructed manganese peroxidase-producing yeast consortium, has been developed to withstand lignin degradation inhibitors while degrading and detoxifying azo dye. MnP-YC4 tolerance to major biomass-derived inhibitors was promising. MnP induced by lignin was found to be highly related to dye decolorization by MnP-YC4. Simulated azo dye-containing wastewater supplemented with a lignin co-substrate (3,5-Dimethoxy-4-hydroxybenzaldehyde) decolorized up to 100, 91, and 76% at final concentrations of 20, 40, and 60%, respectively. MnP-YC4 effectively decolorized the real textile wastewater sample, reaching up to 91.4%, and the COD value decreased significantly during the decolorization, reaching 7160 mg/l within 7 days. A possible dye biodegradation pathway was proposed based on the degradation products identified by UV–vis, FTIR, GC/MS, and HPLC techniques, beginning with azo bond cleavage and eventually mineralized to CO 2 and H 2 O. When compared to the phytotoxic original dye, the phytotoxicity of MnP-YC4 treated dye-containing wastewater samples confirmed the nontoxic nature. [ABSTRACT FROM AUTHOR]

Eutrophication is one of the biggest environmental problems facing wetlands. However, its effect on soil functioning is not yet well understood. We tested the hypothesis that increased nutrient loading into wet grassland ecosystems accelerates soil C and N cycles and decreases microbial immobilization of C and N. Experimental sites were established on two wet grasslands, with either mineral or peaty soils, and fertilized by NPK fertilizer for 3 years. Soils were analyzed for soluble and microbial C and N contents and their transformations, profile of phospholipid fatty acids and number of nirK denitrifiers. Fertilization affected C more than N transformations. Opposite to what was predicted, decomposition was retarded, the soil C cycle was based more on labile C compounds, and the soil was more susceptible to C losses in fertilized versus unfertilized treatments in both soils. Fertilization resulted in lower microbial biomass C and microbial C immobilization and also decreased the activity of lignin-degrading enzymes. Shifts in the composition of the microbial communities led to decreased (1) decomposition of complex organic compounds and (2) immobilization of transformed C. Net nitrification and microbial N immobilization tended to increase in fertilized treatments indicating an acceleration of soil N cycling and losses, but only in the more vulnerable organic soil. [ABSTRACT FROM AUTHOR]

Abstract: An investigation was undertaken on the biodegradation of two kinds of polycyclic aromatic hydrocarbons (PAHs), anthracene (ANT) and benz[a]anthracene (BAA), by fungi isolated from PAH-contaminated mangrove sediments environment in Ma Wan, Hong Kong. ANT (50mg l−1) and BAA (20mg l−1), respectively, were added to mineral salt medium initially for screening of PAH-degrading fungi, and finally two fungal species capable of using ANT or BAA as the sole carbon source were isolated and identified as Fusarium solani species. Removal of ANT and BAA reached 40% and 60% of the added amount, respectively, after 40days of incubation. A total of six metabolites were isolated and characterized by solid phase microextraction (SPME) combined with gas chromatography–mass spectrometry (GC/MS), which indicate that F. solani degraded both ANT and BAA via their respective quinone molecules to generate phthalic acid. Free extracellular laccase was detected during the degradation process without detectable lignin peroxidase (LiP) and manganese-dependent peroxidase (MnP), suggesting that laccase might play an important role in the transformation of PAHs compounds. [ABSTRACT FROM AUTHOR]

Contaminated soil from a historical industrial site and containing sulfide ore ashes and aromatic hydrocarbons underwent sequential leaching by 0.5 M citrate and microbial treatments. Heavy metals leaching was with the following efficiency scale: Cu (58.7%) > Pb (55.1%) > Zn (44.5%) > Cd (42.9%) > Cr (26.4%) > Ni (17.7%) > Co (14.0%) > As (12.4%) > Fe (5.3%) > Hg (1.1%) and was accompanied by concomitant removal of organic contaminants (about 13%). Leached metals were concentrated into an iron gel, produced during ferric citrate fermentation by the metal-resistant strain BAS-10 of Klebsiella oxytoca. Concomitantly, the acidic leached soil was bioaugmented with Allescheriella sp. DABAC 1, Stachybotrys sp. DABAC 3, Phlebia sp. DABAC 9, Pleurotus pulmonarius CBS 664.97, and Botryosphaeria rhodina DABAC P82. B. rhodina was most effective, leading to a significant depletion of the most abundant contaminants, including 7-H-benz[DE]anthracene-7-one, 9,10-anthracene dione and dichloroaniline isomers, and to a marked detoxification as assessed by the mortality test with the Collembola Folsomia candida Willem. The overall degradation activities of B. rhodina and P. pulmonarius appeared to be significantly enhanced by the preliminary metal removal. [ABSTRACT FROM AUTHOR]

The gene of a peroxidase described as being involved in carotenoid degradation was cloned from a strain that was conserved as Lepista irina (CBS 458.79). Gene sequencing revealed high nucleotide and amino-acid identity with Pleurotus eryngii gene vpl , which encodes a versatile peroxidase with unique catalytic properties, and only reported in Pleurotus and Bjerkandera species. Re-identification of the supposed L. irina strain revealed that, in fact, it is a P. eryngii strain. The new P. eryngii peroxidase was expressed in Escherichia coli , and the recombinant protein folded in the presence of cofactor to obtain the active form. The purified enzyme was able to oxidize Mn2+, veratryl alcohol, substituted phenols, and both low and high redox-potential dyes, demonstrating that it belongs to the versatile peroxidase family (named VPL3). These catalytic properties agreed with the presence of both Mn2+ and aromatic-substrate oxidation sites in its molecular structure. [ABSTRACT FROM AUTHOR]

Continuous production of lignin-degrading enzymes by Bjerkandera adusta immobilized on polyurethane foam gave maximum activities of 220 U lignin peroxidase ml-1, 150 U manganese peroxidase ml-1, 50 U laccase ml-1 and 6.2 U protease ml-1 at the retention time of 24 h for 60 days. Protease secretion destabilized the produced lignin peroxidase, manganese peroxidase and laccase. [ABSTRACT FROM AUTHOR]

Peroxidase and laccase activities increased rapidly up to the formation of primordia and then declined throughout the entire stage of fruiting. In the case of Pleurotus ostreatus, the level of Mn-dependent peroxidase was very low in primordia and fruiting stages but gradually increased with the growth of the fruit-body, whereas no activity was detected in Pleurotus sajor-caju during all growth stages. Superoxide dismutase activity was observed mainly at the fruiting stages. These results show that changes in concentration of lignin-related enzymes are associated with the fruiting process. [ABSTRACT FROM AUTHOR]

• A novel Thermothelomyces thermophilus lignin peroxidase (LiP) was produced. • Scale-up production of LiP was conducted in stirred-tank bioreactor at 1.5 L scale. • Different fed-batch strategies (continuous, multi-pulse, and DO-stat) were studied. • Maximum LiP activity of 1,645 mU/L achieved via multi-pulse fed-batch production. • Tangential flow ultrafiltration was effective at concentrating crude LiP. Enzymatic lignin depolymerization is considered a favorable approach to utilize lignin due to the higher selectivity and less energy requirement when compared to thermochemical lignin valorization. Lignin peroxidase (LiP) is one of the key enzymes involved in lignin degradation and possesses high redox potential to oxidize non-phenolic structures and phenolic compounds in lignin. However, the production of LiP is mainly from white-rot fungi at small scales. It is critical to discover new LiP from other microorganisms and produce LiP at large scales. This study aims to produce a novel LiP originally from Thermothelomyces thermophiles using a recombinant Aspergillus nidulans strain. The LiP production medium was optimized, and different fed-batch strategies for LiP production were investigated to improve LiP activity, yield, and productivity. Results demonstrated that LiP production was enhanced by using multi-pulse fed-batch fermentation. A maximum LiP activity of 1,645 mU/L with a protein concentration of 0.26 g/L was achieved. [ABSTRACT FROM AUTHOR]

Spent mushroom substrate (SMS) is an agricultural waste with a high potential for polycyclic aromatic hydrocarbons (PAH) removal in aged contaminated soils. In this study, fresh and air-dried Pleurotus ostreatus , Pleurotus eryngii , and Auricularia auricular SMSs were used to remove PAHs in agricultural soil under 60-day incubation. The potential of SMS in PAH dissipation was studied by detecting the dissipation rate and the soil physicochemical index, enzyme activity, PAH-degradation bacterial biomass, and microbial diversity. Results showed that SMS significantly enhanced the dissipation of PAHs and fresh SMS had a better effect than air-dried SMS. The highest dissipation rate of 16 PAHs was 34.5%, which was observed in soil amended with fresh P. eryngii SMS, and the PAH dissipation rates with low and high molecular weights were 41.3% and 19.4%, respectively. By comparison, fresh P. eryngii SMS presented high nutrient contents, which promoted the development of PAH-degrading bacteria and changed the soil bacterial community involved in degradation, thereby promoting the PAH dissipation. The lignin-degrading enzymes in fresh SMS were abundant, and the laccase and manganese peroxidase activities in the treatment of fresh P. eryngii SMS was higher than those in other treatments. Fresh P. eryngii SMS improved the relative abundance of Microbacterium , Rhizobium , and Pseudomonas in soil, which were all related to PAH degradation. Consequently, adding fresh P. eryngii SMS was an effective method for remediating aged PAH-contaminated agricultural soils. • Fresh SMS is an effective in remediation of PAH-contaminated agricultural soil. • Dissipation rate of PAHs amended with fresh SMS of Pleurotus eryngii was highest. • Fresh SMS promoted growth of PAH-degrading bacteria and diversity of bacteria. • Dissipation rate of PAHs was correlated with soil LaC and MnP activities. [ABSTRACT FROM AUTHOR]

• Large-scale production of aryl alcohol oxidase (AAO) was achieved. • Process parameters of AAO production were optimized. • pH and dissolved oxygen control aided AAO production in stirred-tank bioreactor. • Greatest AAO activity (1906 U/L) and protein concentration (1.19 g/L) were achieved. • Over 6000 U/L AAO was obtained after ultrafiltration. Microbial production of aryl alcohol oxidase (AAO) has attracted increasing attention due to the central role of AAO in enzymatic lignin depolymerization. However, large-scale production of AAO has not been reached because of the low yield and inefficient fermentation process. This study aims to optimize the process parameters and scale-up production of AAO using Aspergillus nidulans in a stirred-tank bioreactor. Effects of pH and dissolved oxygen on AAO production at bioreactor scale were particularly investigated. Results revealed that pH control significantly affected protein production and increasing dissolved oxygen level stimulated AAO production. The greatest AAO activity (1906 U/L) and protein concentration (1.19 g/L) were achieved in 48 h at 60% dissolved oxygen with pH controlled at 6.0. The yield and productivity (in 48 h) were 31.2 U/g maltose and 39.7 U/L/h, respectively. In addition, crude AAO was concentrated and partially purified by ultrafiltration and verified by protein identification. [ABSTRACT FROM AUTHOR]

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

• Cost-effective medium for AAO production by Aspergillus nidulans was developed. • Corn steep liquor provided sufficient nutrients for enzyme production. • Medium components were optimized and validated. • Greatest aryl alcohol oxidase activity (1021 U/L) was achieved. • Protein concentration reached 0.75 g/L. Aryl alcohol oxidase (AAO), an extracellular H 2 O 2 -providing enzyme, plays a central role in lignin depolymerization. Cost-effective production of AAO has not been achieved, due to the low yield of enzyme-producing microorganisms and the high cost of fermentation media. This study aims to develop a cost-effective medium for high-yield production of AAO in submerged culture using a recombinant Aspergillus nidulans strain. Results demonstrate that corn steep liquor (CSL) was a rich but inexpensive nitrogen source for AAO production, and CSL can provide enough trace metals and vitamins (i.e. pyridoxine) for A. nidulans. A 2-level Plackett-Burman design was utilized to determine the main affecting factors in AAO production. The medium was further optimized by a 3-level Box-Behnken design to obtain the optimum medium component concentrations (61.0 g/L maltose, 26.4 g/L CSL, and 13.8 g/L NaNO 3). The greatest AAO activity achieved was 1021 U/L with a protein concentration of 0.75 g/L. [ABSTRACT FROM AUTHOR]