Evaluation of culture conditions for xylose assimilation and secretion of enzymes and peptides by yeasts isolated from the environment

Abstract

In Brazil, sustainable technologies for obtaining bioproducts by fermentative processes are favored by the availability of renewable material as agro-industrial byproducts. Lignocellulosic biomass such as bagasse and sugar cane straw provide hexoses and pentoses which are the substrates for fermentation processes in obtaining of products such as alcohols, organic acids, biosurfactants. In a previous project (Proc. Fapesp 2010 / 12624-0) the enzymatic saccharification of sugarcane bagasse for the production of second generation ethanol was studied, as well as, yeasts capable of assimilating xylose were isolated, identified and characterized . Among these yeasts, several were detected with the ability to produce organic acids from xylose, being necessary the continuity of the investigations of these yeasts and their potential of assimilation of pentoses and the production of biotechnologically important compounds. Preliminary results also indicated the presence of other compounds with a molar mass between 300 and 600 Da, which will be studied in this project. It is known that some yeasts are able to secrete peptides that have biological activities, such as antimicrobial, hence the possibility that some of these compounds are in this category. In addition, other research to be carried out is related to the ability of these yeasts to produce enzymes that hydrolyze hemicellulose, mainly ²-xylosidase and xylan-debranching enzymes such as acetyl xylan esterase and arabinofuranosidase. In this way, we will know the production profiles of these enzymes by these yeasts, besides identifying the protein metabolites released in the medium. During development of this project it is expected to determine the best culture conditions for the assimilation of xylose, to characterize peptides and enzymes secreted by the yeasts in the fermentative medium in semi-solid fermentation