Bioconversão de hidrolisado hemicelulósico de madeira de mimosa tenuiflora wild. Poir em Xilitol.

Abstract

This study investigated the bioconversion of sawdust Mimosa tenuiflora (SMT) by acid hydrolysisand subsequent biotechnological production of xylitol, using yeast Candida tropicalis ATCC750. The higher concentration of xylose was estimated by a Central Composite Design (DCC).In the DCC, the varying concentrations of xylose of H2SO4 (in M) and SMT biomass (% w/v) were evaluated. In autoclaving,the hydrolysis conditions were 121°C for 15 minutes. The concentrations tested were 0.2; 0.6; 1.0 and 1.16 M of H2SO4and 15%, 20%, 25%, and 27.07% of biomass sawdust in nature. The variables that showed significant effects were the acid concentration and the interaction acid between biomass concentrations. The composition of M.tenuiflorahydrolyzate obtained (HMST) in the statistical significant condition of DCC (1.0 M H2SO4 and 25% biomass) was glucose (2.2 g.L-1), xylose (19.2 g.L-1), arabinose (9.9 g.L-1) acetic acid (0.08 g.L-1) and formic acid (6.9 g.L-1). The fermentation of HSMT and synthetic growth medium (SGM) were performed at different temperatures (25, 30 and 35°C), 150 rpm and 100 mL of reaction volume for 72 hours. The significant xylose yieldwithout the presence of inhibitor compounds (furfural and hydroxymethylfurfural) was obtained at 0.6 M of sulfuric acid and 20% (w/v) (19.20 g.L-1) of biomass. When we compared to the SGM, the fermentationof HMSTshowed greater the cell growthand production of xylitol(8.51 g.L-1and 12.68 g.L-1, respectively). Temperature increasecaused reduction in cell growth as well as in the production of xylitol.At25°C, weobtained more favorable conditions for larger production ofxylitol, using the hydrolyzate as a substrate. Finally, the sawdust M. tenuiflora represented a promising biotechnological source to obtain xylitol.