Improvements of xylitol production bioprocess in the biorefinery concept for diversification of product portfolio of sugar-and-alcohol sector

Abstract

Different approaches will be applied to improve the technical and economic feasibility of xylitol production bioprocess from a mixture of sugarcane bagasse and straw in the biorefinery concept for the sugar-alcohol sector. One of the aims is to increase the capacity of the yeast Candida guilliermondii FTI 20037 to bioconvert the xylose present in the hemicellulose to xylitol by optimizing the culture conditions and metabolic pathway engineering. These approaches are based on important progresses achieved at "Escola deEngenharia de Lorena - Universidade de São Paulo", employing this yeast and different biomasses, mainly sugarcane bagasse, as well as on a recent research (FAPESP No.2013/27142-0) in which sugarcane straw was the subject of study. Oxygen supplied, initial concentrations of xylose, sucrose and inoculum will be studied, followed by evaluation of nutritional supplementation of the hydrolysate with sugarcane molasses as a substitution of sucrose and an additional source of nitrogenous compounds and minerals. Regarding the metabolic pathway engineering, C. guilliermondii FTI 20037 will be sequentially transformed by attenuation of xylitol dehydrogenase, over-expression of xylose reductase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and attenuation of phosphoglucoisomerase. The third approach corresponds to the evaluation of the feasibility of using the cellulignin residue from this bioprocess for nanocellulose production, a high-added value biomaterial with application ranging from civil construction to medicine. It is expected that the outcomes of this project will contribute to product diversification of the sugar alcohol sector creating opportunities for integral utilization of sugarcane bagasse and straw, as well as of molasses, in the biorefinery concept. (AU)