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André Ferraz - One of the best experts on this subject based on the ideXlab platform.

  • Effect of aqueous extracts from Ceriporiopsis subvermispora-biotreated wood on the decolorization of Azure B by Fenton-like reactions
    International Biodeterioration & Biodegradation, 2012
    Co-Authors: André Aguiar, André Ferraz
    Abstract:

    Abstract Aqueous extracts from wood biotreated with the white-rot fungus Ceriporiopsis subvermispora were evaluated for their Fe 3+ - and Cu 2+ -reducing activities and their anti- or prooxidant properties in Fenton-like reactions to decolorize the recalcitrant dye Azure B. The decolorization of Azure B was strongly inhibited in the presence of 10% (v/v) wood extracts. Only 0.1% (v/v)-diluted extracts provided some enhancement of the Azure B decolorization. The iron-containing reactions decolorized more Azure B and consumed substantially more H 2 O 2 than the reactions containing copper. This study demonstrates that water-soluble wood phenols exert anti- or prooxidant effects that depend on their concentration in the reactions and on the type of cation, Fe 3+ or Cu 2+ , used to convert H 2 O 2 to OH radicals.

  • Effects of exogenous calcium or oxalic acid on Pinus taeda treatment with the white-rot fungus Ceriporiopsis subvermispora
    International Biodeterioration & Biodegradation, 2012
    Co-Authors: André Aguiar, André Ferraz
    Abstract:

    Abstract Pinus taeda wood chips were treated with the biopulping fungus Ceriporiopsis subvermispora in calcium- or oxalic acid-amended cultures. The secretion of hydrolytic and oxidative enzymes was inhibited only in the cultures having the highest concentration of calcium (1400 mg kg −1 wood). Calcium decreased the availability of free oxalic acid, inhibited fungal growth, and reduced lignin mineralization and transformations. Oxalic acid amendment in the cultures was found not to affect the lignin mineralization and transformations; however, it did inhibit the depolymerization reactions detectable in the residual lignin that was retained in the biotreated wood. C. subvermispora presented catabolic activity for oxalic acid in the cultures amended with 1660 mg acid kg −1 wood, whereas oxalic acid was synthesized when it was amended at low amounts or initially absent in the cultures. These data suggest one ideal ratio of oxalic acid in C. subvermispora cultures and indicate that its exogenous addition does not necessarily accompany the further degradation of lignin.

  • uso de aditivos na biodegradacao de madeira pelo fungo Ceriporiopsis subvermispora efeito na peroxidacao de lipidios dependente de manganes peroxidase
    Química Nova, 2012
    Co-Authors: André Aguiar, André Ferraz
    Abstract:

    Ceriporiopsis subvermispora is a selective fungus in the wood delignification and the most promising in biopulping. Through the lipid peroxidation initiated by manganese peroxidase (MnP), free radicals can be generated, which can act in the degradation of lignin nonphenolic structures. This work evaluated the prooxidant activity (based in lipid peroxidation) of enzymatic extracts from wood biodegradation by this fungus in cultures containing exogenous calcium, oxalic acid or soybean oil. It was observed that MnP significant activity is required to promote lipid peroxidation and wood delignification. Positive correlation between prooxidant activity x MnP was observed up to 300 IU kg-1 of wood.

  • linoleic acid peroxidation initiated by fe3 reducing compounds recovered from eucalyptus grandis biotreated with Ceriporiopsis subvermispora
    International Biodeterioration & Biodegradation, 2011
    Co-Authors: Maria Augusta Crivelente Horta, Jaime Rodríguez, Fernando Masarin, André Ferraz
    Abstract:

    Abstract This work evaluates linoleic acid peroxidation reactions initiated by Fe 3+ -reducing compounds recovered from Eucalyptus grandis , biotreated with the biopulping fungus Ceriporiopsis subvermispora . The aqueous extracts from biotreated wood had the ability to reduce Fe 3+ ions from freshly prepared solutions. The compounds responsible for the Fe 3+ -reducing activity corresponded to UV-absorbing substances with apparent molar masses from 3 kDa to 5 kDa. Linoleic acid peroxidation reactions conducted in the presence of Fe 3+ ions and the Fe 3+ -reducing compounds showed that the rate of O 2 consumption during peroxidation was proportional to the Fe 3+ -reducing activity present in each extract obtained from biotreated wood. This peroxidation reaction was coupled with in-vitro treatment of ball-milled E. grandis wood. Ultraviolet data showed that the reaction system released lignin fragments from the milled wood. Size exclusion chromatography data indicated that the solubilized material contained a minor fraction representing high-molar-mass molecules excluded by the column and a main low-molar-mass peak. Overall evaluation of the data suggested that the Fe 3+ -reducing compounds formed during wood biodegradation by C. subvermispora can mediate lignin degradation through linoleic acid peroxidation.

  • Behavior of Ceriporiopsis subvermispora during Pinus taeda biotreatment in soybean-oil-amended cultures
    International Biodeterioration & Biodegradation, 2010
    Co-Authors: André Aguiar, Regis Teixeira Mendonça, Jaime Rodríguez, André Ferraz
    Abstract:

    Abstract Pinus taeda wood chips were treated with the biopulping fungus Ceriporiopsis subvermispora in soybean-oil-amended cultures. The secretion of oxalic acid and the accumulation of thiobarbituric acid reactive substances were significantly increased in soybean-oil-amended cultures. By contrast, the secretion of hydrolytic and oxidative enzymes was not altered in the cultures. Biotreated wood samples were characterized for weight and component losses as well as by in-situ thioacidolysis. Residual lignins were also extracted from biotreated wood using a mild-non-razing extraction procedure. The lignins were characterized by 31P nuclear magnetic resonance (31P-NMR) spectroscopy. Soybean oil amendment in the cultures was found to affect lignin degradation routes; however, it inhibited depolymerization reactions detectable in the residual lignin that was retained in the biotreated wood. As a consequence, chemithermomechanical pulping of the biotreated samples was not improved by soybean oil amendment in the cultures.

Takashi Watanabe - One of the best experts on this subject based on the ideXlab platform.

  • Cerebrosides, extracellular glycolipids secreted by the selective lignin-degrading fungus Ceriporiopsis subvermispora
    Chemistry and Physics of Lipids, 2017
    Co-Authors: Hiroshi Nishimura, Daisuke Yamaguchi, Takashi Watanabe
    Abstract:

    Abstract Ceriporiopsis subvermispora is a selective white-rot fungus that degrades lignin at a site far from the hyphae and extracellular enzymes, without intensive damage to the cellulose. In selective ligninolysis, low molecular mass metabolites play a principal role and amphipathic substances are involved to control the degradation and transport of hydrophobic aromatic molecules, including lignin and lipids; however, secretion of the amphipathic substances by this fungus has not been well understood, except for alk(en)yl itaconates called ceriporic acids, which have a weak amphiphilicity. Herein, we report for the first time that the fungus secretes cerebrosides that are classified as glycosphingolipids. By using liquid chromatography electron spray ionization mass spectrometry (LC-ESI–MS) and nuclear magnetic resonance (NMR) spectroscopy coupled with stable isotope feeding experiments with 13C-glucose and 15N-ammonium sulfate, the cerebrosides were determined to be N-hydroxyoctadecanoyl-1-O-β- d -glucopyranosyl-4E,8E-sphingadienine, N-hydroxyoctadecanoyl-1-O-β- d -glucopyranosyl-4E,8Z-sphingadienine, and N-hydroxyoctadecanoyl-1-O-β- d -glucopyranosyl-9-methyl-4E,8E-sphingadienine. The cerebrosides are strong amphipathic substances and potential metabolites for regulating difference and symbiosis within the microbial community.

  • Structural characterization of highly branched glucan sheath from Ceriporiopsis subvermispora.
    International Journal of Biological Macromolecules, 2016
    Co-Authors: Daisuke Suzuki, Hiroshi Nishimura, Koichi Yoshioka, Rumi Kaida, Takahisa Hayashi, Keiji Takabe, Takashi Watanabe
    Abstract:

    Wood rotting basidiomycetes produce extracellular mucilaginous sheaths interfacing fungal hyphae and plant biomass. While the versatility of these fungal sheaths has been addressed, sheaths generated by selective white-rot fungi remain poorly understood. To fill this gap, the sheath produced by the basidiomycete Ceriporiopsis subvermispora, which degrades lignin while inflicting limited cellulose damage, was analyzed in this study. Fluorescence and transmission electron microscopy revealed that the sheath formed three days after inoculation into a beech wood slice on an agar plate and was embedded at the interface between fungal hyphae and wood cell walls. The sheath's chemical structure was evaluated from fungus cultures in a liquid medium containing [U-13C6]-d-glucose and beech wood slices. Compositional analysis, methylation analysis, and 13C NMR demonstrated that the sheath mainly consisted of a comb-like β-1,6-glucopyranose residue-branched β-1,3-glucan, which is advantageous to retain water and extracellular secondary metabolites.

  • alkadienyl and alkenyl itaconic acids ceriporic acids g and h from the selective white rot fungus Ceriporiopsis subvermispora a new class of metabolites initiating ligninolytic lipid peroxidation
    Organic and Biomolecular Chemistry, 2012
    Co-Authors: Hiroshi Nishimura, Midori Sasaki, Hirofumi Seike, Masaharu Nakamura, Takashi Watanabe
    Abstract:

    New ceriporic acids—alkadienyl and alkenyl itaconic acids having a bis-allyl (3-[(Z,Z)-hexadec-7,10-dienyl]-itaconic acid; ceriporic acid G) and a monoene (3-[(Z)-octadec-9-enyl]-itaconic acid; ceriporic acid H) structure in their side chains—were isolated from the cultures of the selective lignin-degrading fungus Ceriporiopsis subvermispora. The new metabolites ceriporic acid G and H were synthesized by a cross-aldol condensation and a Grignard substitution reaction, respectively. Ceriporic acid G triggered the manganese peroxidase (MnP)-catalyzed lipid peroxidation and decomposed a recalcitrant non-phenolic lignin substructure model compound. Except for simple fatty acids, this is the first report of a fungal metabolite that induced ligninolytic lipid peroxidation.

  • surface carbohydrate analysis and bioethanol production of sugarcane bagasse pretreated with the white rot fungus Ceriporiopsis subvermispora and microwave hydrothermolysis
    Bioresource Technology, 2011
    Co-Authors: Chizuru Sasaki, Yoichi Honda, Takahito Watanabe, Rie Takada, Shuichi Karita, Yoshitoshi Nakamura, Takashi Watanabe
    Abstract:

    Abstract Effects of pretreatments with a white rot fungus, Ceriporiopsis subvermispora, and microwave hydrothermolysis of bagasse on enzymatic saccharification and fermentation were evaluated. The best sugar yield, 44.9 g per 100 g of bagasse was obtained by fungal treatments followed by microwave hydrothermolysis at 180 °C for 20 min. Fluorescent-labeled carbohydrate-binding modules which recognize crystalline cellulose (CjCBM3-GFP), non-crystalline cellulose (CjCBM28-GFP) and xylan (CtCBM22-GFP) were applied to characterize the exposed polysaccharides. The microwave pretreatments with and without the fungal cultivation resulted in similar levels of cellulose exposure, but the combined treatment caused more defibration and thinning of the plant tissues. Simultaneous saccharification and fermentation of the pulp fractions obtained by microwave hydrothermolysis with and without fungal treatment, gave ethanol yields of 35.8% and 27.0%, respectively, based on the holocellulose content in the pulp. These results suggest that C. subvermispora pretreatment could be beneficial part of the process to produce ethanol from bagasse.

  • Epoxy ceriporic acid produced by selective lignin-degrading fungus Ceriporiopsis subvermispora.
    Chemistry and Physics of Lipids, 2011
    Co-Authors: Hiroshi Nishimura, Yoichi Honda, Yuichi Setogawa, Takahito Watanabe, Takashi Watanabe
    Abstract:

    Abstract Ceriporiopsis subvermispora is a selective white rot basidiomycete which degrades lignin in wood at a distance far from enzymes. Low molecular mass metabolites play a central role in the oxidative degradation of lignin. To understand the unique wood-decaying mechanism, we surveyed the oxidized derivatives of ceriporic acids (alk(en)ylitaconic acids) produced by C. subvermispora using high-resolution liquid chromatography multiple-stage mass spectrometry (HR-LC/MSn). The analysis of the precursor and product ions from the extract suggested that an epoxidized derivative of ceriporic acid is produced by the fungus. To identify the new metabolite, an authentic compound of ceriporic acid epoxide was synthesized in vitro by reacting (R)-3-[(Z)-hexadec-7-enyl]-itaconic acid (ceriporic acid C) with m-chloroperbenzoic acid. The precursor and product ions from the natural metabolite and authentic epoxide were identical and distinguishable from those of hydroxy and hydroperoxy derivatives after reduction with NaBD4. Feeding experiments with [U-13C]-glucose, 99% and the subsequent analyses of the first and second generation product ions demonstrated that the oxidized ceriporic acid was (R)-3-(7,8-epoxy-hexadecyl)-itaconic acid. To our knowledge, this study is the first to report that natural alkylitaconic acid bears an epoxy group on its side chain.

Juanita Freer - One of the best experts on this subject based on the ideXlab platform.

  • Kraft pulping and ECF bleaching of Eucalyptus globulus pretreated by the white-rot fungus Ceriporiopsis subvermispora
    Acta Scientiarum-technology, 2012
    Co-Authors: Claudio Salazar, Regis Teixeira Mendonça, Jaime Baeza, Juanita Freer
    Abstract:

    Eucalyptus globulus wood chips were decayed by the lignin-degrading fungus Ceriporiopsis subvermispora as a pretreatment step before kraft pulping. Weight and component losses of wood after the biotreatment were the following: weight (5%), glucans (1.5%), xylans (4.3%), lignin (5.7%) and extractives (57.5%). The residual amount of lignin (expressed by the kappa number) in pulps from biotreated wood chips was lower than that of pulps from the undecayed control. Depending on the delignification degree, kraft biopulps presented similar or up to 4% increase in pulp yield and 20% less hexenuronic acids (HexA) than control pulps. The extended delignification with O2 decreases approximately 50% of the kappa number of the pulps and increases brightness, but had no effect in HexA reduction. The bleaching steps with chlorine dioxide (D0ED1 sequence) decreased the kappa number up to 97%, increased pulp brightness up to 84% ISO and decreased HexA amount up to 91%. The use of C. subvermispora in biopulping of E. globulus generated important benefits during the production of kraft pulps that are reflected in a high pulp yield, low residual lignin content, low HexA amount, high brightness and viscosity of the biopulps as compared with pulps produced from untreated wood chips.

  • linoleic acid peroxidation and lignin degradation by enzymes produced by Ceriporiopsis subvermispora grown on wood or in submerged liquid cultures
    Enzyme and Microbial Technology, 2010
    Co-Authors: Gina Gabriela Seabra Cunha, Juanita Freer, Fernando Masarin, Marcela Norambuena, André Ferraz
    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.

  • Evaluation of the white-rot fungi Ganoderma australe and Ceriporiopsis subvermispora in biotechnological applications
    Journal of Industrial Microbiology and Biotechnology, 2008
    Co-Authors: Regis Teixeira Mendonça, José Francisco Jara, Juan Pedro Elissetche, Victor Gonzalez, Juanita Freer
    Abstract:

    Ganoderma australe is a white-rot fungus that causes a selective wood biodelignification in some hardwoods found in the Chilean rainforest. Ceriporiopsis subvermispora is also a lignin-degrading fungus used in several biopulping studies. The enzymatic system responsible for lignin degradation in wood can also be used to degrade recalcitrant organic pollutants in liquid effluents. In this work, two strains of G. australe and one strain of C. subvermipora were comparatively evaluated in the biodegradation of ABTS and the dye Poly R-478 in liquid medium, and in the pretreatment of Eucalyptus globulus wood chips for further kraft biopulping. Laccase was detected in liquid and wood cultures with G. australe. Ceriporiopsis subvermispora produce laccase and manganese peroxidase when grown in liquid medium and only manganese peroxidase was detected during wood decay. ABTS was totally depleted by all strains after 8 days of incubation while Poly R-478 was degraded up to 40% with G. australe strains and up to 62% by C. subvermispora after 22 days of incubation. Eucalyptus globulus wood chips decayed for 15 days presented 1-6% of lignin loss and less than 2% of glucan loss. Kraft pulps with kappa number 15 were produced from biotreated wood chips with 2% less active alkali, with up to 3% increase in pulp yield and up to 20% less hexenuronic acids than pulps from undecayed control. Results showed that G. australe strains evaluated were not as efficient as C. subvermispora for dye and wood biodegradation, but could be used as a feasible alternative in biotechnological processes such as bioremediation and biopulping.

  • Kraft pulping of Eucalyptus nitens wood chips biotreated by Ceriporiopsis subvermispora
    Journal of Chemical Technology & Biotechnology, 2006
    Co-Authors: Lorena Mardones, Juanita Freer, José Lívio Gomide, André Ferraz, Jaime Rodríguez
    Abstract:

    Eucalyptus nitens and E. globulus are wood species used in kraft pulping in Chile and Australia. Although E. nitens adapts very well to cold regions it requires more severe cooking conditions to produce bleachable kraft pulps. An attempt was made to find out whether a pre-treatment with Ceriporiopsis subvermispora would improve its performance during kraft pulping and the pulp properties. The biotreatment of the chips carried out for a period of 15 days resulted in 13.3% lignin loss and a limited glucan degradation (2%). The pulping of biotreated samples required lower active alkali charge to reach the target kappa number compared to the control untreated sample and exhibited better pulping selectivity. The pulp yield increased by 3% and 1.5% for the pulps of 22 and 16 kappa numbers, respectively. The biotreated pulp's strength properties were improved and were similar to those of E. globulus reference pulp. Copyright © 2006 Society of Chemical Industry

  • Near‐Infrared Spectra and Chemical Characteristics of Pinus taeda (Loblolly Pine) Wood Chips Biotreated by the White‐Rot Fungus Ceriporiopsis subvermispora
    Journal of Wood Chemistry and Technology, 2005
    Co-Authors: André Ferraz, Regis Teixeira Mendonça, Jaime Rodríguez, Jaime Baeza, Anderson Guerra, José Ruiz, Juanita Freer
    Abstract:

    Abstract Near‐infrared (NIR) spectroscopy was evaluated as an analytical tool for monitoring changes in Pinus taeda (loblolly pine) induced by the white‐rot fungus Ceriporiopsis subvermispora. Intensities of several NIR bands increased with biodegradation time, but a direct correlation between band intensities and biodegradation periods or weight losses due to the biotreatment were not observed. On the other hand, the intensities of NIR bands correlated with properties reflecting the macromolecular characteristics of the components of the biotreated wood samples. Bio‐kraft pulps were also characterized by wet chemical analysis and NIR spectroscopy. In this case, appropriate prediction models related NIR spectral information with the chemical composition of the pulps, r 2 values ranged from 0.96 to 0.99.

Yoichi Honda - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of the effects of terminators and introns on recombinant gene expression in the basidiomycete Ceriporiopsis subvermispora
    Journal of Microbiology, 2020
    Co-Authors: Dong Xuan Nguyen, Emi Nishisaka, Moriyuki Kawauchi, Takehito Nakazawa, Masahiro Sakamoto, Yoichi Honda
    Abstract:

    Terminators and introns are vital regulators of gene expression in many eukaryotes; however, the functional importance of these elements for controlling gene expression in Agaricomycetes remains unclear. In this study, the effects of Ceriporiopsis subvermispora terminators and introns on the expression of a recombinant hygromycin B phosphotransferase gene (hph) were characterized. Using a transient transformation system, we proved that a highly active terminator (e.g., the gpd terminator) is required for the efficient expression of the hph gene. Mutational analyses of the C. subvermispora gpd terminator revealed that hph expression was dictated by an A-rich region, which included a putative positioning element, and polyadenylation sites. In contrast, our results indicated that introns are not required for the expression of hph directed by the Csβ1-tub and Csgpd promoters in C. subvermispora . This study provides insights into the functions and cis-element requirements of transcriptional terminators in Agaricomycetes, which may be relevant for designing recombinant genes for this important fungal class.

  • surface carbohydrate analysis and bioethanol production of sugarcane bagasse pretreated with the white rot fungus Ceriporiopsis subvermispora and microwave hydrothermolysis
    Bioresource Technology, 2011
    Co-Authors: Chizuru Sasaki, Yoichi Honda, Takahito Watanabe, Rie Takada, Shuichi Karita, Yoshitoshi Nakamura, Takashi Watanabe
    Abstract:

    Abstract Effects of pretreatments with a white rot fungus, Ceriporiopsis subvermispora, and microwave hydrothermolysis of bagasse on enzymatic saccharification and fermentation were evaluated. The best sugar yield, 44.9 g per 100 g of bagasse was obtained by fungal treatments followed by microwave hydrothermolysis at 180 °C for 20 min. Fluorescent-labeled carbohydrate-binding modules which recognize crystalline cellulose (CjCBM3-GFP), non-crystalline cellulose (CjCBM28-GFP) and xylan (CtCBM22-GFP) were applied to characterize the exposed polysaccharides. The microwave pretreatments with and without the fungal cultivation resulted in similar levels of cellulose exposure, but the combined treatment caused more defibration and thinning of the plant tissues. Simultaneous saccharification and fermentation of the pulp fractions obtained by microwave hydrothermolysis with and without fungal treatment, gave ethanol yields of 35.8% and 27.0%, respectively, based on the holocellulose content in the pulp. These results suggest that C. subvermispora pretreatment could be beneficial part of the process to produce ethanol from bagasse.

  • Epoxy ceriporic acid produced by selective lignin-degrading fungus Ceriporiopsis subvermispora.
    Chemistry and Physics of Lipids, 2011
    Co-Authors: Hiroshi Nishimura, Yoichi Honda, Yuichi Setogawa, Takahito Watanabe, Takashi Watanabe
    Abstract:

    Abstract Ceriporiopsis subvermispora is a selective white rot basidiomycete which degrades lignin in wood at a distance far from enzymes. Low molecular mass metabolites play a central role in the oxidative degradation of lignin. To understand the unique wood-decaying mechanism, we surveyed the oxidized derivatives of ceriporic acids (alk(en)ylitaconic acids) produced by C. subvermispora using high-resolution liquid chromatography multiple-stage mass spectrometry (HR-LC/MSn). The analysis of the precursor and product ions from the extract suggested that an epoxidized derivative of ceriporic acid is produced by the fungus. To identify the new metabolite, an authentic compound of ceriporic acid epoxide was synthesized in vitro by reacting (R)-3-[(Z)-hexadec-7-enyl]-itaconic acid (ceriporic acid C) with m-chloroperbenzoic acid. The precursor and product ions from the natural metabolite and authentic epoxide were identical and distinguishable from those of hydroxy and hydroperoxy derivatives after reduction with NaBD4. Feeding experiments with [U-13C]-glucose, 99% and the subsequent analyses of the first and second generation product ions demonstrated that the oxidized ceriporic acid was (R)-3-(7,8-epoxy-hexadecyl)-itaconic acid. To our knowledge, this study is the first to report that natural alkylitaconic acid bears an epoxy group on its side chain.

  • Characterization of a Δ12-fatty acid desaturase gene from Ceriporiopsis subvermispora, a selective lignin-degrading fungus
    Applied Microbiology and Biotechnology, 2010
    Co-Authors: Takahito Watanabe, Yoichi Honda, Hiroshi Nishimura, Saeko Tsuda, Takashi Watanabe
    Abstract:

    Ceriporiopsis subvermispora, a white-rot fungus, is characterized as one of the best biopulping fungi because it can degrade lignin selectively without serious damage to cellulose. We previously demonstrated that during the early stage of wood decay, this fungus produces large amounts of linoleic acid (18:2n-6) and degrades lignin by manganese peroxidase-catalyzed lipid peroxidation. In this study, we cloned a Δ12-fatty acid desaturase gene absolutely essential for the biosynthesis of linoleic acid as the main substrate for lipid peroxidation. This gene designated Cs-fad2 encodes a protein with three histidine-rich domains and four membrane-spanning domains characteristic of other Δ12-fatty acid desaturases. Moreover, we heterologously expressed Cs-fad2 in Saccharomyces cerevisiae lacking Δ12-fatty acid desaturase, and detected the de novo biosynthesis of linoleic acid by gas chromatography–mass spectrometry analysis. We also investigated transcription of Cs-fad2 under various conditions. The transcription was activated and repressed in the presence of a lignin fragment and exogenous fatty acids, respectively. These results may shed light on the molecular relationship between fatty acid metabolism and selective lignin degradation in C. subvermispora.

  • Absolute configuration of ceriporic acids, the iron redox-silencing metabolites produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora.
    Chemistry and Physics of Lipids, 2009
    Co-Authors: Hiroshi Nishimura, Yoichi Honda, Takahito Watanabe, Kyoko Murayama, Takashi Watanabe
    Abstract:

    Abstract Ceriporic acids are a class of alk(en)ylitaconic acids produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora. The unique function of alkylitaconic acid is the redox silencing of the Fenton reaction system by inhibiting reduction of Fe3+. Ceriporic acids have an asymmetric centre at carbon-3, but absolute configuration has not been determined. We have isolated a series of ceriporic acids from the cultures of C. subvermispora, and measured their NMR spectra using a chiral shift reagent. In comparison with NMR spectra of (R)-(−)- and (S)-(+)-methylsuccinic acid and those of natural and chemically synthesized racemic mixtures of ceriporic acids, we have determined the absolute configuration of ceriporic acids as (R)-3-tetradecylitaconic acid (ceriporic acid A), (R)-3-hexadecylitaconic acid (ceriporic acid B) and (R,Z)-2-(hexadec-7-enyl)-3-itaconic acid (ceriporic acid C). We herein discuss their stereoselective biosynthetic pathway and the structural diversity of fungal secondary metabolites.

Rafael Vicuña - One of the best experts on this subject based on the ideXlab platform.

  • Effect of manganese on the secretion of manganese-peroxidase by the basidiomycete Ceriporiopsis subvermispora.
    Fungal Genetics and Biology, 2010
    Co-Authors: Rodrigo A. Mancilla, Paulo Canessa, Augusto Manubens, Rafael Vicuña
    Abstract:

    The ligninolytic machinery of the widely used model fungus Ceriporiopsis subvermispora includes the enzymes manganese-peroxidase (MnP) and laccase (Lcs). In this work the effect of Mn(II) on the secretion of MnP was studied. Cultures grown in the absence of Mn(II) showed high levels of mnp transcripts. However, almost no MnP enzyme was detected in the extracellular medium, either by enzymatic activity assays or Western blot hybridizations. In the corresponding mycelia, immuno-electron microscopy experiments showed high levels of MnP enzyme within intracellular compartments. These results suggest that in addition to its well-known effect on transcription regulation of mnp genes, manganese influences secretion of MnP to the extracellular medium. Experiments carried out in the presence of cycloheximide confirmed that the metal is required to secrete MnP already synthesized and retained within the cell.

  • cellobiose dehydrogenase from the ligninolytic basidiomycete Ceriporiopsis subvermispora
    Applied and Environmental Microbiology, 2009
    Co-Authors: Wolfgang Harreither, Evelyn Dunhofen, Rafael Vicuña, Christoph Sygmund, Dietmar Haltrich, Roland Ludwig
    Abstract:

    Cellobiose dehydrogenase (CDH), an extracellular flavocytochrome produced by several wood-degrading fungi, was detected in cultures of the selective delignifier Ceriporiopsis subvermispora when grown on a cellulose- and yeast extract-based liquid medium. CDH amounted to up to 2.5% of total extracellular protein during latter phases of the cultivation and thus suggested an important function for the fungus under the given conditions. The enzyme was purified 44-fold to apparent homogeneity. It was found to be present in two glycoforms of 98 kDa and 87 kDa with carbohydrate contents of 16 and 4%, respectively. The isoelectric point of both glycoforms is around 3.0, differing by 0.1 units, which is the most acidic value so far reported for a CDH. By using degenerated primers of known CDH sequences, one cdh gene was found in the genomic DNA, cloned, and sequenced. Alignment of the 774-amino-acid protein sequence revealed a high similarity to CDH from other white rot fungi. One notable difference was found in the longer interdomain peptide linker, which might affect the interdomain electron transfer at higher temperatures. The preferred substrate of C. subvermispora CDH is cellobiose, while glucose conversion is strongly discriminated by a 155,000-fold-lower catalytic efficiency. This is a typical feature of a basidiomycete CDH, as are the acidic pH optima for all tested electron acceptors in the range from 2.5 to 4.5.

  • Hydroquinone and H2O2 differentially affect the ultrastructure and expression of ligninolytic genes in the basidiomycete Ceriporiopsis subvermispora
    Fems Microbiology Letters, 2009
    Co-Authors: Alejandro Amoroso, Rodrigo A. Mancilla, Bernardo González, Rafael Vicuña
    Abstract:

    The biodegradation of lignin is a highly oxidative process in which various oxidases and peroxidases play a major role. During lignin decay, the generation of aromatic compounds and reactive oxygen species leads to oxidative stress. In this work, the effect of the oxidative compounds H2O2 and hydroquinone in the ligninolytic fungus Ceriporiopsis subvermispora was studied, both at the ultrastructural and at the transcriptional level. Transmission electron microscopy revealed the presence of microvesicles and extensive cytoplasm degeneration after incubation with hydroquinone, but not with H2O2. Studies of the intracellular redox state of the fungus showed that hydroquinone causes a transient decrease in the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio and an increase in the glutathione-S-transferase mRNA levels. These results suggest that hydroquinone produces oxidative stress in this microorganism. On the other hand, it was observed that hydroquinone, but not H2O2, affects Mn-dependent peroxide and laccase transcripts levels. We propose that the mechanism by which the fungus reacts against oxidative stress contributes to its selectivity toward lignin during wood decay.

  • Analysis of manganese-regulated gene expression in the ligninolytic basidiomycete Ceriporiopsis subvermispora
    Current Genetics, 2008
    Co-Authors: Matías Gutiérrez, Rafael Vicuña, Daniela Seelenfreund, Luis Alejandro Rojas, Rodrigo Mancilla-villalobos, Sergio Lobos
    Abstract:

    In this work, we explore the use of the unbiased cDNA–AFLP strategy to identify genes involved in Mn^2+ homeostasis in Ceriporiopsis subvermispora . In this ligninolytic white-rot fungus, whose genome has not yet been sequenced, three Mn peroxidase genes responding to Mn^2+ have been characterized. Using cDNA–AFLP to identify transcript-derived fragments (TDFs), a total of 37 differentially expressed cDNA fragments were identified by comparing band intensities among cDNA–AFLP patterns obtained from mycelia from cultures supplemented with different concentrations of Mn^2+. Of 21 differentially expressed TDFs, nine were classified as upregulated, five as downregulated and seven as unregulated. Of these, six upregulated and two downregulated TDFs were selected for further characterization. The expected TDFs for the known Mn peroxidases were not isolated, but several genes encoding proteins related to protein sorting, storage and excretion of excess Mn^2+ were identified. Transcripts induced under Mn^2+ supplementation exhibited homologies to the elongation factor eEF3, a HDEL sequence binding protein and the ARD1 subunit of the N -acetyltransferase complex, among others. Overall, the results obtained in this study suggest a complex picture of Mn^2+ homeostasis and provide the possibility to search for common regulatory elements in the promoters of the novel putatively identified genes.

  • Manganese affects the production of laccase in the basidiomycete Ceriporiopsis subvermispora.
    Fems Microbiology Letters, 2007
    Co-Authors: Augusto Manubens, Loreto Salas, Paulo Canessa, Carolina Folch, Marcela Avila, Rafael Vicuña
    Abstract:

    The authors have previously identified and characterized lcs, a gene encoding laccase in the white-rot basidiomycete Ceriporiopsis subvermispora. In this work, the effect of Mn2+ in the production of extracellular laccase in liquid cultures of this fungus has been assessed. It was observed that at low (0-10 microM) concentrations of Mn2+, high titers of lcs-mRNA were obtained, whereas at high (160-194 microM) concentrations of this metal ion, transcripts levels decreased markedly. This phenomenon was observed at different days of growth. On the other hand, Cu2+ or Ag+, but not Zn2+ or Cd2+, led to an accumulation of lcs transcripts only in cultures grown in the absence of Mn2+. A dramatic increase in lcs transcript levels was also obtained with syringic acid, a lignin-related aromatic compound. This effect was more pronounced in cultures lacking Mn2+. In the course of these studies it was observed that Mn2+ stimulates mycelium growth. Thus, although extracellular laccase activity appeared higher in cultures containing 160 or 194 microM Mn2+, i.e. when lcs transcripts were lower, a correlation between lcs-mRNA levels and enzymatic activity was observed when values of the latter were corrected by the amount of mycelium present in the cultures.