Production of xylanase and beta-xylosidase from autohydrolysis liquor of corncob using two fungal strains

Agroindustrial residues are materials often rich in cellulose and hemicellulose. The use of these substrates for the microbial production of enzymes of industrial interest is mainly due to their high availability associated with their low cost. In this work, corncob (CCs) particles decomposed to soluble compounds (liquor) were incorporated in the microbial growth medium through autohydrolysis, as a strategy to increase and undervalue xylanase and beta-xylosidase production by Aspergillus terricola and Aspergillus ochraceus. The CCs autohydrolysis liquor produced at 200 A degrees C for 5, 15, 30 or 50 min was used as the sole carbon source or associated with untreated CC. The best condition for enzyme synthesis was observed with CCs submitted to 30 min of autohydrolysis. The enzymatic production with untreated CCs plus CC liquor was higher than with birchwood xylan for both microorganisms. A. terricola produced 750 total U of xylanase (144 h cultivation) and 30 total U of beta-xylosidase (96-168 h) with 0.75% untreated CCs and 6% CCs liquor, against 650 total U of xylanase and 2 total U of beta-xylosidase in xylan; A. ochraceus produced 605 total U of xylanase and 56 total U of beta-xylosidase (168 h cultivation) with 1% untreated CCs and 10% CCs liquor against 400 total U of xylanase and 38 total U of beta-xylosidase in xylan. These results indicate that the treatment of agroindustrial wastes through autohydrolysis can be a viable strategy in the production of high levels of xylanolytic enzymes.

Conformational stability of recombinant manganese superoxide dismutase from the filamentous fungus Trichoderma reesei

Superoxide dismutases (SODS; EC 1.15.1.1) are part of the antioxidant system of aerobic organisms and are used as a defense against oxidative injury caused by reactive oxygen species (ROS). The cloning and sequencing of the 788-bp genomic DNA from Trichoderma reesei strain QM9414 (anamorph of Hypocrea jecorina) revealed an open reading frame encoding a protein of 212 amino acid residues, with 65-90% similarity to manganese superoxide dismutase from other filamentous fungi. The TrMnSOD was purified and shown to be stable from 20 to 90 degrees C for 1 h at pH from 8 to 11.5, while maintaining its biological activity. (C) 2011 Elsevier B.V. All rights reserved.

Gamma Irradiation of in-Shell and Blanched Peanuts Protects against Mycotoxic Fungi and Retains Their Nutraceutical Components during Long-Term Storage

Peanut samples were irradiated (0.0, 5.2, 7.2 or 10.0 kGy), stored for a year (room temperature) and examined every three months. Mycotoxic fungi (MF) were detected in non-irradiated blanched peanuts. A dose of 5.2 kGy was found suitable to prevent MF growth in blanched samples. No MF was detected in in-shell peanuts, with or without irradiation. The colors of the control in-shell and blanched samples were, respectively, 44.72 and 60.21 (L *); 25.20 and 20.38 (Chroma); 53.05 and 86.46 (degrees Hue). The water activities (Aw) were 0.673 and 0.425. The corresponding fatty acids were 13.33% and 12.14% (C16:0), 44.94% and 44.92% (C18:1,omega 9) and 37.10% and 37.63% (C18: 2,omega 6). The total phenolics (TP) were 4.62 and 2.52 mg GAE/g, with antioxidant activities (AA) of 16.97 and 10.36 mu mol TEAC/g. Storage time negatively correlated with Aw (in-shell peanuts) or L *, linoleic acid, TP and AA (in-shell and blanched peanuts) but positively correlated with Aw (blanched peanuts), and with oleic acid (in-shell and blanched peanuts). Irradiation positively correlated with antioxidant activity (blanched peanuts). No correlation was found between irradiation and AA (in-shell samples) or fatty acids and TP (in-shell and blanched peanuts). Irradiation protected against MF and retained both the polyunsaturated fatty acids and polyphenols in the samples.

Mycobiota and mycotoxins in Brazil nut samples from different states of the Brazilian Amazon region

The objective of this study was to evaluate the presence of fungi and mycotoxins (aflatoxins and cyclopiazonic acid) in Brazil nut samples collected in different states of the Brazilian Amazon region: Acre, Amazonas, Amapa, and Para. A total of 200 husk samples and 200 almond samples were inoculated onto Aspergillus flavus-parasiticus agar for the detection of fungi. Mycotoxins were analyzed by high-performance liquid chromatography. The mycobiota comprised the following fungi, in decreasing order of frequency: almonds - Phialemonium spp. (54%), Penicillium spp. (16%), Fusarium spp. (13%), Phaeoacremonium spp. (11%), and Aspergillus spp. (4%), husks - Phialemonium spp. (62%), Phaeoacremonium spp. (11%), Penicillium spp. (10%), Fusarium spp. (9%), and Aspergillus spp. A polyphasic approach was used for identification of Aspergillus species. Aflatoxins were detected in 22 (11%) of the 200 almond samples, with 21 samples presenting aflatoxin B-1 levels above 8 mu g/kg, the limit established by the European Commission for Brazil nuts for further processing. Nineteen (9.5%) of the 200 husk samples contained aflatoxins, but at levels lower than those seen in almonds. Cyclopiazonic acid (CPA) was detected in 44 (22%) almond samples, with levels ranging from 98.65 to 1612 mu g/kg. Aspergillus nomius and A. flavus were the most frequent Aspergillus species. The presence of fungi does not necessarily imply mycotoxin contamination, but almonds of the Brazil nut seem to be a good substrate for fungal growth. (C) 2012 Elsevier B.V. All rights reserved.

Biosynthesis of Two Dihydropyrrole-Polyketides from a Marine-Derived Penicillium citrinum

Feeding experiments with C-13-labeled precursors were performed in order to establish the biosynthesis of two N-acylated dihydropyrroles, (8E)-1-(2,3-dihydro-1H-pyrrol-1-yl)-2- methyldec-8-ene-1,3-dione (1) and 1-(2,3-dihydro-1H-pyrrol-1-yl)-2- methyldecane-1,3-dione (2), isolated from the cultures of a marine-derived Penicillium citrinum. The biosynthesis of both, 1 and 2, involves the incorporation of acetate, methionine and ornithine.

Metabolic engineering of beta-oxidation in Penicillium chrysogenum for improved semi-synthetic cephalosporin biosynthesis

Industrial production of semi-synthetic cephalosporins by Penicillium chrysogenum requires supplementation of the growth media with the side-chain precursor adipic acid. In glucose-limited chemostat cultures of P. chrysogenum, up to 88% of the consumed adipic acid was not recovered in cephalosporinrelated products, but used as an additional carbon and energy source for growth. This low efficiency of side-chain precursor incorporation provides an economic incentive for studying and engineering the metabolism of adipic acid in P. cluysogenum. Chemostat-based transcriptome analysis in the presence and absence of adipic acid confirmed that adipic acid metabolism in this fungus occurs via beta-oxidation. A set of 52 adipate-responsive genes included six putative genes for acyl-CoA oxidases and dehydrogenases, enzymes responsible for the first step of beta-oxidation. Subcellular localization of the differentially expressed acyl-CoA oxidases and dehydrogenases revealed that the oxidases were exclusively targeted to peroxisomes, while the dehydrogenases were found either in peroxisomes or in mitochondria. Deletion of the genes encoding the peroxisomal acyl-CoA oxidase Pc20g01800 and the mitochondrial acyl-CoA dehydrogenase Pc20g07920 resulted in a 1.6- and 3.7-fold increase in the production of the semi-synthetic cephalosporin intermediate adipoyl-6-APA, respectively. The deletion strains also showed reduced adipate consumption compared to the reference strain, indicating that engineering of the first step of beta-oxidation successfully redirected a larger fraction of adipic acid towards cephalosporin biosynthesis. (C) 2012 Elsevier Inc. All rights reserved.

Tratamento de água com hidrocarbonetos aromáticos por uso de reator em bateladas sequenciais com inoculo fúngico

Um reator em batelada, aerado, com biomassa imobilizada de Aspergillus niger AN400 foi operado durante 10 ciclos de 7 dias para remover benzeno (200 mg.L-1), tolueno (200 mg.L-1) e xileno (50 mg.L-1) - BTX - e de nutrientes de meio basal. O reator era alimentado semanalmente com 4 L do meio e glicose - 1 g.L-1, na Fase I, e 0,5 g.L-1, na Fase II. Os BTX foram detectados até o quarto dia de operação, em todos os ciclos. As melhores eficiências médias de remoção foram na Fase I: 75%de matéria orgânica solúvel, 80% de ortofosfato e 77% de amônia. O reator pode ser uma alternativa viável para tratamento de águas poluídas com BTX, porém há a necessidade de estudar o comportamento do reator durante período de operação mais longo e com ciclos reacionais mais curtos, bem como da identificação dos metabólitos produzidos.

The capability of endophytic fungi for production of hemicellulases and related enzymes

Abstract Background There is an imperative necessity for alternative sources of energy able to reduce the world dependence of fossil oil. One of the most successful options is ethanol obtained mainly from sugarcane and corn fermentation. The foremost residue from sugarcane industry is the bagasse, a rich lignocellulosic raw material uses for the production of ethanol second generation (2G). New cellulolytic and hemicellulytic enzymes are needed, in order to optimize the degradation of bagasse and production of ethanol 2G. Results The ability to produce hemicellulases and related enzymes, suitable for lignocellulosic biomass deconstruction, was explored using 110 endophytic fungi and 9 fungi isolated from spoiled books in Brazil. Two initial selections were performed, one employing the esculin gel diffusion assay, and the other by culturing on agar plate media with beechwood xylan and liquor from the hydrothermal pretreatment of sugar cane bagasse. A total of 56 isolates were then grown at 29°C on steam-exploded delignified sugar cane bagasse (DEB) plus soybean bran (SB) (3:1), with measurement of the xylanase, pectinase, β-glucosidase, CMCase, and FPase activities. Twelve strains were selected, and their enzyme extracts were assessed using different substrates. Finally, the best six strains were grown under xylan and pectin, and several glycohydrolases activities were also assessed. These strains were identified morphologically and by sequencing the internal transcribed spacer (ITS) regions and the partial β-tubulin gene (BT2). The best six strains were identified as Aspergillus niger DR02, Trichoderma atroviride DR17 and DR19, Alternaria sp. DR45, Annulohypoxylon stigyum DR47 and Talaromyces wortmannii DR49. These strains produced glycohydrolases with different profiles, and production was highly influenced by the carbon sources in the media. Conclusions The selected endophytic fungi Aspergillus niger DR02, Trichoderma atroviride DR17 and DR19, Alternaria sp. DR45, Annulohypoxylon stigyum DR47 and Talaromyces wortmannii DR49 are excellent producers of hydrolytic enzymes to be used as part of blends to decompose sugarcane biomass at industrial level.

Monitoring and determination of fungi and mycotoxins in stored Brazil nuts

Brazil nut (Bertholletia excelsa) is an important commodity from the Brazilian Amazon, and approximately 37,000 tons (3.36 × 10⁷ kg) of Brazil nuts are harvested each year. However, substantial nut contamination by Aspergillus section Flavi occurs, with subsequent production of mycotoxins. In this context, the objective of the present investigation was to evaluate the presence of fungi and mycotoxins (aflatoxins and cyclopiazonic acid) in 110 stored samples of cultivated Brazil nut (55 samples of nuts and 55 samples of shells) collected monthly for 11 months in Itacoatiara, State of Amazonas, Brazil. The samples were inoculated in duplicate onto Aspergillus flavus and Aspergillus parasiticus agar and potato dextrose agar for the detection of fungi, and the presence of mycotoxins was determined by high-performance liquid chromatography. The most prevalent fungi in nuts and shells were Aspergillus spp., Fusarium spp., and Penicillium spp. A polyphasic approach was used for identification of Aspergillus species. Aflatoxins and cyclopiazonic acid were not detected in any of the samples analyzed. The low water activity of the substrate was a determinant factor for the presence of fungi and the absence of aflatoxin in Brazil nut samples. The high frequency of isolation of aflatoxigenic Aspergillus section Flavi strains, mainly A. flavus, and their persistence during storage increase the chances of aflatoxin production on these substrates and indicates the need for good management practices to prevent mycotoxin contamination in Brazil nuts.

Isolation of Sporothrix schenckii from the claws of domestic cats (indoor and outdoor) and in captivity in São Paulo (Brazil)

Sporotrichosis is a subcutaneous mycosis and is also a zoonosis (sapro- and anthropozoonosis). The objective of the present study was to determine the occurrence of sporotrichosis in domestic cats and in wild or exotic felines in captivity through the isolation of Sporothrix spp. from claw impressions in a culture medium. The samples included 132 felines, of which 120 (91.0 %) were domestic cats, 11 (8.3 %) were wild felines, and one (0.7 %) was an exotic felid. Twenty-one (17.5 %) were outdoor cats. Of the total, 89 (67.4 %) had contact with other animals of the same species. It was possible to isolate Sporothrix schenckii from the claws of one (0.7 %) of the felids probed; this animal exhibited generalised sporotrichosis and had infected a female veterinarian. The potential pathogenic agents Microsporum canis and Malassezia pachydermatis were isolated in 12.1 and 5.3 % of the animals, respectively. The following anemophilous fungi, which were considered to be contaminants, were also isolated: Penicillium sp. (28 or 21.2 %), Aspergillus sp. (13 or 9.8 %), Rhodotorula sp. (5 or 3.8 %), Candida sp. (5 or 3.8 %), Trichoderma sp. (1 or 0.7 %), and Acremonium sp. (1 or 0.7 %). Due to the low magnitude of occurrence (0.7 %) of Sporothrix in feline claws, the potential of the cats evaluated in this study to be sources of infection in the city of São Paulo is considerably low.

Mycobiota, aflatoxins and cyclopiazonic acid in stored peanut cultivars

This study evaluated the presence of fungi and mycotoxins [aflatoxins (AFs), cyclopiazonic acid (CPA), and aspergillic acid] in stored samples of peanut cultivar Runner IAC Caiapó and cultivar Runner IAC 886 during 6 months. A total of 70 pod and 70 kernel samples were directly seeded onto Aspergillus flavus and Aspergillus parasiticus agar for fungi isolation and aspergillic acid detection, and AFs and CPA were analyzed by high-performance liquid chromatography. The results showed the predominance of Aspergillus section Flavi strains, Aspergillus section Nigri strains, Fusarium spp., Penicillium spp. and Rhizopus spp. from both peanut cultivars. AFs were detected in 11.4% of kernel samples of the two cultivars and in 5.7% and 8.6% of pod samples of the Caiapó and 886 cultivars, respectively. CPA was detected in 60.0% and 74.3% of kernel samples of the Caiapó and 886 cultivars, respectively. Co-occurrence of both mycotoxins was observed in 11.4% of kernel samples of the two cultivars. These results indicate a potential risk of aflatoxin production if good storage practices are not applied. In addition, the large number of samples contaminated with CPA and the simultaneous detection of AFs and CPA highlight the need to investigate factors related to the control and co-occurrence of these toxins in peanuts.

The capability of endophytic fungi for production of hemicellulases and related enzymes

Abstract BACKGROUND: There is an imperative necessity for alternative sources of energy able to reduce the world dependence of fossil oil. One of the most successful options is ethanol obtained mainly from sugarcane and corn fermentation. The foremost residue from sugarcane industry is the bagasse, a rich lignocellulosic raw material uses for the production of ethanol second generation (2G). New cellulolytic and hemicellulytic enzymes are needed, in order to optimize the degradation of bagasse and production of ethanol 2G. RESULTS: The ability to produce hemicellulases and related enzymes, suitable for lignocellulosic biomass deconstruction, was explored using 110 endophytic fungi and 9 fungi isolated from spoiled books in Brazil. Two initial selections were performed, one employing the esculin gel diffusion assay, and the other by culturing on agar plate media with beechwood xylan and liquor from the hydrothermal pretreatment of sugar cane bagasse. A total of 56 isolates were then grown at 29°C on steam-exploded delignified sugar cane bagasse (DEB) plus soybean bran (SB) (3:1), with measurement of the xylanase, pectinase, β-glucosidase, CMCase, and FPase activities. Twelve strains were selected, and their enzyme extracts were assessed using different substrates. Finally, the best six strains were grown under xylan and pectin, and several glycohydrolases activities were also assessed. These strains were identified morphologically and by sequencing the internal transcribed spacer (ITS) regions and the partial β-tubulin gene (BT2). The best six strains were identified as Aspergillus niger DR02, Trichoderma atroviride DR17 and DR19, Alternaria sp. DR45, Annulohypoxylon stigyum DR47 and Talaromyces wortmannii DR49. These strains produced glycohydrolases with different profiles, and production was highly influenced by the carbon sources in the media. CONCLUSIONS: The selected endophytic fungi Aspergillus niger DR02, Trichoderma atroviride DR17 and DR19, Alternaria sp. DR45, Annulohypoxylon stigyum DR47 and Talaromyces wortmannii DR49 are excellent producers of hydrolytic enzymes to be used as part of blends to decompose sugarcane biomass at industrial level.