Otimização in silico da produção de xilitol por Saccharomyces cerevisiae a partir de material hemicelulósico

Abstract

Lignocellulosic materials comprise solid urban, industrial, agricultural and wood residues that are the target of several researches with the objective of producing several products with higher added value. Its composition contains a hemicellulosic fraction that when undergoing a pre-treatment generates fermentable sugars such as D-xylose which, by the action of a microorganism, can be converted into xylitol. In turn, xylitol is a polyalcohol with applications in the food and beverage industry, in medicine and dentistry, and obtaining it biochemically is still a challenge. Among the microorganisms capable of producing xylitol, yeasts from the strains of the genera Candida, Pichia and Saccharomyces are some of the most studied. Thus, in this context, the objective of this work was to evaluate in silico, using some optimization methods available in the opensource software OptFlux, the genetic modifications with the potential to increase the production of xylitol from hemicellulosic material in the metabolism of the yeast Saccharomyces cerevisiae, which has a favorable database and is already used industrially to obtain ethanol. The highest production of xylitol was 11.96 mmol/gDCW/h obtained with only 5 changes in the metabolic model of yeast, of which four reactions present in the Glycolysis pathway were deleted and one reaction present in the Pentose and Glucuronate interconversions pathway, which contains the target metabolite xylitol, was under-expressed.