Desenvolvimento de bioprocesso utilizando fungos filamentosos amazônicos, visando aplicação no pré-tratamento biológico de biomassas vegetais

Abstract

Several microorganisms are known as good producers of enzymes with the ability to hydrolyze plant biomass. Fungi of the phylum Basidiomycetes such as Trametes sp. are considered to be excellent producers of ligninolytic enzymes and fungi of the phylum Ascomycetes such as Aspergillus sp. and Penicillium sp. are considered in the literature to be good producers of cellulolytic enzymes. These enzymes are of great industrial interest as they can be used in a wide variety of processes. Therefore, the aim of this study was to pre-treat corn crop residue (straw) using Amazonian fungi in order to increase hydrolytic efficiency. The residue in natura and after pre-treatment was characterized in terms of cellulose, hemicellulose and lignin content, as well as assessing structural changes after pre-treatment. The presence of the enzymes cellulases, hemicellulases (xylanases) and ligninases (lacases, lignin peroxidases and manganese peroxidases) was determined in each pre-treatment. The best cellulase activity detected was that of Fpase with an activity of 6.6 U/mg after 5 days of fermentation using the co-cultivation of Aspergillus oryzase plus Trametes versicolor. The best xylanase production showed an activity of 1.74 U/mg using the mono-culture of Penicillium citrinum and the best ligninase production was lacases with an activity of 29.4 U/mg using the fungus Trametes versicolor in mono-culture. In terms of lignin content, the cultures that showed the best removal of this component were the mono-cultures of Trametes versicolor and Aspergillus oryzae, with 36% and 22% removal, respectively. On the other hand, the cultures that showed the best changes in the structure of the corn straw cell wall were the co-cultures containing Penicillium citrinum plus Trametes versicolor and the co- culture where all three fungi were present (Aspergillus oryzae, Penicillium citrinum and Trametes versicolor). In general, the microbial consortium showed promising results for adding value to waste from the agro-industry. The waste in natura and after biological pre- treatment with the fungi A. oryzae, P. citrinum and T. versicolor in mono and co-cultivation were evaluated for hydrolytic efficiency, showing 7.3% hydrolytic efficiency in the biomass in natura and 90% hydrolytic efficiency after pre-treatment with T. versicolor in mono and co- cultivation. T. versicolor in monoculture, demonstrating that the biological pre-treatment was able to convert the sugars present in the corn straw, which is a fundamental stage in the biomass saccharification process.