The fermentation by using pentoses is an essential step to improve the production yield of ethanol and organic acids from lignocellulosic material. In Brazil, advances in technologies for the production of second generation bioethanol are favored by the availability and variety of renewable raw materials (agro-industrial byproducts). In this area, in recent years, the research group coordinated by Dra Eleni Gomes has focused her studies on the prospection of fungi for degradation of plant biomass. In these studies, several yeasts with ability to assimilate pentoses were isolated from the environment. Some yeasts have been able to grow in xylose or arabinose as a carbon source. However, other yeasts, although consuming 80-100% of the xylose or arabinose, they showed a little biomass and did not produce ethanol or xylitol. Several of the strains studied were able to tolerate phenolic derivatives and grown in sugarcane bagasse. In view of these results, it is agreed that the assimilation of pentoses and the microbial growth using these sugars imply in the existence of an efficient system of transport through the membrane. Thus, we believe in the need for continuity of studies with these yeasts considering the potential of pentoses assimilation, in order to improve the utilization of these sugars from the hydrolysis of plant biomass. Additionally, we sought to understand the ability of these yeast for assimilating xylose and arabinose to produce the enzyme ²-xylosidase - a rare enzyme in its extracellular form. Thus, considering that the physiology of the yeasts for assimilating pentoses is not well known, it will be necessary a study directed to investigate the efficiency in the assimilation of the pentoses, as well as, what would be the byproducts formed from the consumption of the pentoses, like the acids Organic. In the present project, we intend to investigate more deeply some of these yeasts with capacity for L-arabinose and xylose assimilation, they are: Aureobasidium leucospermi LB86, Candida oleophila G10.1, Issachenkia terricola G20 and Pichia guilliermondii G1.2. Our intention is to investigate the byproducts obtained and to improve our knowledge about the pentose transport system and to provide subsidies to the metabolic engineering of yeasts. During the realization of this project we hope to obtain differentiated results, and at the end of the work, contribute to the advancement in the knowledge on the assimilation of pentoses by yeasts, in order to improve application methodologies for the production of second generation bioethanol and organic acid byproducts, for Fermentation medium of pentoses derived from hemicellulose hydrolysis.
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