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Abstract: Delignification of corn stover by the white rot fungus Ceriporiopsis subvermispora in solid-state cultivation was evaluated for improving subsequent enzymatic hydrolysis. The results showed that C. subvermispora selectively degraded lignin by as much as 39.2% while the cellulose loss was less than 5% during 42d of cultivation. However, hemicellulose loss of up to 27.0% was concomitant with the lignin degradation. Ligninolytic enzymes, MnP and laccase, were detected during degradation of corn stover by C. subvermispora. For major hydrolytic enzymes, xylanase was the only enzyme detected. The enzymatic hydrolysis yield of corn stover delignified by C. subvermispora was remarkably improved, reaching about 57–67% overall glucose yield after 18–42d of pretreatment, while the glucose yield of the untreated was only 22%. A higher overall glucose yield of about 72% was obtained when the enzymatic hydrolysis of the 18d treated corn stover was supplemented with an accessory xylanase/cellulase enzyme complex. [Copyright &y& Elsevier]

Abstract: Ceriporiopsis subvermispora is a white-rot fungus used in biopulping processes and seems to use the fatty acid peroxidation reactions initiated by manganese-peroxidase (MnP) to start lignin degradation. The present work shows that C. subvermispora was able to peroxidize unsaturated fatty acids during wood biotreatment under biopulping conditions. In vitro assays showed that the extent of linoleic acid peroxidation was positively correlated with the level of MnP recovered from the biotreated wood chips. Milled wood was treated in vitro by partially purified MnP and linoleic acid. UV spectroscopy and size exclusion chromatography (SEC) showed that soluble compounds similar to lignin were released from the milled wood. SEC data showed a broad elution profile compatible with low molar mass lignin fractions. MnP-treated milled wood was analyzed by thioacidolysis. The yield of thioacidolysis monomers recovered from guaiacyl and syringyl units decreased by 33% and 20% in MnP-treated milled wood, respectively. This has suggested that lignin depolymerization reactions have occurred during the MnP/linoleic acid treatment. [Copyright &y& Elsevier]

Abstract: The degradation of the components of Japanese beech and Japanese cedar wood was measured over time in cultures of the white-rot fungus Ceriporiopsis subvermispora. Although there was no initial degradation of cedar wood, after 12 weeks the mass loss of both cedar and beech wood was 15–20%. The mass losses of filter paper in beech wood-containing cultures and glucose cultures after 12 weeks were 87% and 70%, respectively. The ratio of lignin loss to mass loss of both beech and cedar wood cultures approached 2.0. Although the cellulose loss in cedar wood was very low throughout the 12-week incubation, C. subvermispora degraded the hemicellulose in Japanese cedar much more effectively than that in Japanese beech. These results confirm that C. subvermispora is a selective lignin degrader. During the 12-week incubation with Japanese beech wood, C. subvermispora continuously produced at least one of three phenol oxidases: laccase was produced initially, followed by Mn-independent peroxidase activity peaking at 6 weeks and Mn-dependent peroxidase activity peaking at 10 weeks. Lignin peroxidase and carboxymethylcellulase activities peaked after 3 weeks of incubation. Avicelase activity was present throughout the incubation period, although the activity was very low. The low-molecular-mass fraction of the extracellular medium, which catalyzes a redox reaction between O2 and electron donors to produce hydroxyl radical, may act synergistically with the enzymes to degrade wood cell walls. [Copyright &y& Elsevier]

Abstract: Ceriporiopsis subvermispora was utilized for the biodegradation of Eucalyptus grandis in the presence or absence of co-substrates (glucose and corn steep liquor) during 7, 14 and 28 days. The biodegraded chips were used to prepare enzymatic extracts that, after pre-treatment with activated charcoal, were enriched in activity of manganese peroxidases (MnPs) with anion-exchange chromatography followed by elution with NaCl. Samples of these extracts were then analyzed by denaturing electrophoresis in order to compare the profiles of proteins and MnPs. Depending on the biodegradation period and on the presence or absence of co-substrates in the culture, one or two major proteins (relative molecular weights of 46.8±0.6 and 51.6±1.0kDa) were identified. The presence of MnPs activity was further confirmed by native electrophoresis followed by phenol red staining. [Copyright &y& Elsevier]

Abstract: Eucalyptus grandis biodegradation by Ceriporiopsis subvermispora in solid-state cultures supplemented with corn steep liquor (CSL), glucose and Mn2+ was evaluated. Chemical composition of biotreated wood was determined to correlate the extent of wood transformation with the levels of extracellular agents produced during fungal growth. Manganese-dependent peroxidases and xylanases were detected under all culture conditions. The lowest and the highest MnP activities were observed in cultures supplemented with Mn2+ and CSL/glucose (178 and 1317IUkg−1 of dry wood, respectively). In all cultures, glucan and xylan losses were lower than 3% while lignin loss varied from 2.7% to 9%. Lignin loss was correlated with the cleavage of aryl-ether linkages detected with basis on derivatization followed by reductive cleavage (DFRC) analysis. The highest lignin loss and the lowest yield of DFRC monomers were observed in cultures supplemented with Mn2+ and CSL. This culture condition presented intermediate levels of MnP production. Oxalate production was not strongly affected by addition of culture supplements suggesting that oxalate was not a limiting agent during wood degradation by C. subvermispora. Conversely, the results suggest that a compromise between the levels of MnP and Mn2+ was necessary to promote intense degradation of lignin revealed by DFRC analysis and lignin mass balances. [Copyright &y& Elsevier]

Abstract: Pinus taeda wood chips were treated with the biopulping fungus, Ceriporiopsis subvermispora, under solid-state fermentation for periods varying from 7 to 90 days. Low molecular mass compounds and oxidative enzymes were extracted from biotreated wood samples. Manganese-dependent peroxidase was the main oxidative enzyme on all biodegradation periods. Aqueous extracts from biotreated wood presented decreasing pH values, oxalic acid being the major organic acid secreted by the fungus. Analysis of these extracts by gas chromatography coupled with mass spectrometry (GC/MS) revealed small amounts of fatty acids, several short-chain organic acids (C3–C6) and numerous sugar derivatives. 3-methoxy-4-hydroxy benzaldehyde, 3-methoxy-4-hydroxy benzoic acid, 3,4-dihydroxy benzoic acid and tricarboxy-benzene were also found in the wood extracts. A remarkable characteristic of the wood extracts was a strong Fe3+-reducing ability. High Fe3+-reducing activity and high catechol concentrations were detected in the wood extracts from the undecayed control. This reducing activity and catechol concentrations decreased during the first 7 days of biodegradation. However, from the seventh day of culturing, catechol derivatives coming from lignin degradation start to accumulate in the cultures and Fe3+-reduction activity increased again. The Fe3+-reduction activity observed in the wood extracts indicates that Fe2+ would be available in solution during the wood decay process. Considering that Fe2+ and H2O2 (produced by this fungus based on MnP-degradation of oxalate) were present in the wood extracts, at least some extent for degradation reactions based on Fenton-chemistry, similarly to the observed in brown-rot fungi, is supposed to occur during wood decay by C. subvermispora. [Copyright &y& Elsevier]

Abstract: Production of cellulases and hemicellulases by Ceriporiopsis subvermispora cultured on wood chips of Eucalyptus grandis and Pinus taeda was studied. Xylanase, endo-1,4 β-glucanase, mannanase, β-glucosidase and β-xylosidase were detected in enzymatic extracts obtained after 30 days of cultivation. P. taeda gave rise to higher enzyme production compared to E. grandis. Biochemical characteristics of cellulases and hemicellulases produced in both wood species were almost the same. The optimum pH for the enzymes was between 4.0 and 5.0 and the optimum temperature was 60°C. Thermal stability of the enzymes at pH 5.0 was appreciable up to 50°C. The profile of proteins contained in extracts recovered from both biotreated wood species showed a similar number of bands during SDS-PAGE electrophoresis. Five bands with molecular weight ranging from 50 to 85kDa and two bands with high molecular weight (100–200kDa) were observed. Activity staining for xylanases indicated two enzymes with molecular weight of 80 and 33kDa. [Copyright &y& Elsevier]

Abstract: NAD-dependent formate dehydrogenase (FDH, EC 1.2.1.2.) was purified 34-fold with 5.8% yield as an electrophoretically homogeneous protein from the white-rot fungus Ceriporiopsis subvermispora. The native enzyme has a molecular mass of 84kDa consisting of two identical subunits as a homodimer. The K m values for formate and NAD were found to be 2.5mM and 28μM, respectively, at the optimum pH 6.5. The enzyme activity was inhibited by NADH, ADP, and ATP. The kinetic analysis indicated that the enzyme reaction proceeded by the ordered Bi Bi mechanism. Oxalate was found to be catabolized by mediations of oxalate decarboxylase (ODC, EC 4.1.1.2) and FDH during the vegetative growth of C. subvermispora, while it was oxidized by oxalate oxidase (OXO, EC 1.2.3.4) at the later stage of the cultivation. A possible role of the two-oxalate decomposing systems with ODC and OXO was discussed in relation to carbon metabolism of lignin-degrading basidiomycetes. [Copyright &y& Elsevier]

Ceriporiopsis subvermispora is a white-rot basidiomycete that degrades lignin selectively and often is used in biopulping. Development of appropriate experimental procedures for recovery and determination of enzymes produced by C. subvermispora during biopulping is necessary to evaluate the role of each enzyme in this process. In this work, enzymes produced during biopulping were extracted and determined by using a series of substrates. Manganese-dependent peroxidases (MnP) predominated over laccases, which were of minor significance. The lack of laccases was further confirmed by assaying several substrates such as syrindaldazine, o-dianisidine and ABTS. A basal oxidation of syringaldazine and phenol red in the absence of exogenous Mn2+ led to the assumption that the extracts contained some Mn-independent peroxidase or enough Mn2+ to initiate MnP catalyzed reactions. The presence of Mn2+ was evidenced since phenol red was not oxidized by a 16-h-dialysed extract. Addition of 111 μM of Mn2+ to the reaction medium restored the oxidative activity. Lignin peroxidase activity was not detected in the extracts based on the Azure B assay. Cellulase activities were very low while xylanases predominated. The xylanolytic complex was deficient in beta-xylosidase. Successive extractions were performed for a quantitative recovery of the enzymes adsorbed on wood chips. The first 4-h extraction recovered an average of 50% of the total enzymatic activities. [Copyright &y& Elsevier]

Significant contributions have been made to understand the ligninolytic system of the biopulping fungus, Ceriporiopsis subvermispora; however, the reason why this fungus selectively degrades lignin is still unclear. This study evaluates the depolymerization of wood components induced by C. subvermispora during wood decay under solid-state fermentation. Pinus taeda wood chips were biotreated for periods from 15 to 90 days. The fungus degraded lignin and extractives extensively without removing large amounts of glucan. Alpha-cellulose samples were prepared from decayed and undecayed wood chips for evaluation of cellulose depolymerization. The yields of alpha-cellulose decreased from 47.8% for undecayed wood to 42.6 and 34.2% for the wood samples biotreated for 30 and 90 days, respectively. High performance size exclusion chromatography of tricarbanyl derivatives of these alpha-cellulose preparations indicated a progressive decrease in the polymerization degree values from the 30th day of biotreatment. Lignin depolymerization, evaluated by gel permeation chromatography (GPC) of residual MWLs, was rapid in the first 30 days of biodegradation. After this period an extensive mineralization occurred. Some relevant hydrolytic and oxidative enzymes present in the culture extracts were studied. Xylanase was the main hydrolytic enzyme produced, while laccase was not detected in any biodegradation period evaluated. A correlation between the levels of wood-degrading enzymes produced and the pattern of wood constituents degradation was tentatively established. [Copyright &y& Elsevier]

The white-rot fungus Ceriporiopsis subvermispora grows on wood aggressively and is suitable for biopulping of both soft and hardwoods. This fungus is able to produce laccase and manganese peroxidase (MnP) isoenzymes, as well as hemicellulases and a poor complex of cellulases lacking in cellobiohydrolase activity. In the present work, C. subvermispora was grown on Eucalyptus grandis wood chips under solid-state fermentation. Wood weight loss ranged from 2.9 to 11.7% for biodegradation periods of 15–90 days. The highest lignin loss was 27 %, which was similar to the loss of polyoses (21.6%) after 90 days of treatment. Glucan loss started to be significant only after 60 days of biodegradation attaining a maximum of 7.3% after 90 days. Extractives removal was also significant, reaching 42% after 90 days. Holocellulose yields were almost unchanged over all the biodegradation periods. However, the holocellulose viscosities decreased as a function of the biodegradation time, especially after 30 days. The yields of alpha-cellulose decreased from 44 to 37% as a function of the biodegradation time, indicating that cellulose depolymerization took place even when the glucan losses were low. Some relevant hydrolytic and oxidative enzymes present in the culture extracts were studied. Xylanase was the main hydrolytic enzyme and the levels of peroxidase were lower than those of laccase. During the initial wood decay stages, there was not a direct correlation between the levels of enzymatic activities and the extent of losses of wood weight or components. This suggests that the mineralization of wood components might be limited by the non-diffusion of the enzymes into the wood cell walls at the initial decay stages. [Copyright &y& Elsevier]