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

Abstract

BackgroundThere 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.ResultsThe 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.ConclusionsThe 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.

Diversity and distribution of the endophytic fungal community in eucalyptus leaves

“…Endophytic microorganisms can colonize plants via wounds at lateral root emergence sites (Hallman et al, 1997) or by releasing hydrolytic enzymes (Robl et al, 2013) that allow them to enter and colonize the plants (Hallman et al, 1997).…”

Xylanase production by endophyticAspergillus nigerusing pentose-rich hydrothermal liquor from sugarcane bagasse

“…imman et al (2013) obtained high levels of hemicellulose in the liquid phase and improvement in the enzymatic hydrolysis of hydrothermally pretreated sugarcane bagasse. the liquor from the hydrothermal sugarcane bagasse pretreatment contains high concentrations of xylose and xylo-oligosaccharides (Robl et al 2013), and could be used as a substrate for xylanase production. michelin et al (2012b) used the liquor from the hydrothermal pretreatment of wheat straw to produce xylanase with Aspergillus ochraceus.…”

“…michelin et al (2012b) used the liquor from the hydrothermal pretreatment of wheat straw to produce xylanase with Aspergillus ochraceus. Robl et al (2013) screened hemicellulase producers using the pentose-rich liquor from hydrothermal pretreatment of sugarcane bagasse. even though this material is a promising feedstock for xylanase induction, due to its high contents of xylo-oligomers and xylose, the high concentrations of compounds such as furfurals, organic acids, and soluble phenols can hamper fungal growth.…”

“…the aim of this work was to contribute to the development of a submerged fermentation process producing a hemicellulase enzyme cocktail using the endophytic A. niger DR02 strain (Robl et al 2013) grown on the pentose-rich liquor from sugarcane bagasse hydrothermal pretreatment. the enzymatic cocktails produced using batch and fed-batch procedures were characterized and used as cellulolytic enzyme supplements in order to enhance the enzymatic hydrolysis of pretreated sugarcane bagasse.…”

Rapid microbiological tests for prospecting new fungal strains with high potentiality for the pectinolytic enzymes production

“…Robl et al (2013) analyzed the enzymatic production of hemicelullases and related enzymes, with use of agar aesculin and agar with specific substrate evaluating the halo degradation for the initial selection. Glinka and Liao (2011) analyzed the production of pectin metilesterase (PME), polygalacturonase (PG) and pectin lyase (PL) through activity tests in the agar diffusion assays.…”