Evaluation of Inoculum of <I>Candida guilliermondii </I>Grown in Presence of Glucose on Xylose Reductase and Xylitol Dehydrogenase Activities and Xylitol Production During Batch Fermentation of Sugarcane Bagasse Hydrolysate

Abstract

The effect of glucose on xylose-xylitol metabolism in fermentation medium consisting of sugarcane bagasse hydrolysate was evaluated by employing an inoculum of Candida guilliermondii grown in synthetic media containing, as carbon sources, glucose (30 g/L), xylose (30 g/L), or a mixture of glucose (2 g/L) and xylose (30 g/L). The inoculum medium containing glucose promoted a 2.5-fold increase in xylose reductase activity (0.582 IU/mgprot) and a 2-fold increase in xylitol dehydrogenase activity (0.203 IU/mgprot) when compared with an inoculum-grown medium containing only xylose. The improvement in enzyme activities resulted in higher values of xylitol yield (0.56 g/g) and productivity (0.46 g/[L.h]) after 48 h of fermentation.

Evaluation of hexose and pentose in pre-cultivation of Candida guilliermondii on the key enzymes for xylitol production in sugarcane hemicellulosic hydrolysate

“…However, only part of the arabinose was consumed (data not shown). A similar behaviour of C. guilliermondii yeast in sugarcane bagasse hydrolysate was reported by Silva et al (2005) and Sarrouh et al (2009). Also, it was observed total acetic acid consumption independently of carbon source used during the inoculum growth (data not shown).…”

“…2). Silva et al (2005) using the same yeast, but a different sugarcane hemicellulosic hydrolysate treatment observed an improvement in xylose consumption by using an inoculum previously growth in a mixture of glucose and xylose. This behavior could be explained by the multiple uptake systems for D-xylose assimilation, for example according to Lucas and van Uden (1986) when C. shehatae was grown on either D-glucose or D-xylose it produces a facilitated diffusion system which can transport D-glucose with high affinity/low capacity, while D-xylose transportation is low affinity/high capacity.…”

“…As observed by enzymes activities, the highest glycerol (1.32 g l -1 ) and ethanol (3.20 g l -1 ) production were favored by using inoculum previously grown in both sugars followed by inoculum previously grown in xylose or in glucose. According to Silva et al (2005) the highest glycerol formation were observed when C. guilliermondii was previously grown in both sugars and xylose, respectively using sugarcane bagasse hydrolysate as a fermentation medium.…”

Xylitol production from wheat straw hemicellulosic hydrolysate: hydrolysate detoxification and carbon source used for inoculum preparation

“…Such findings suggest that the cheaper sugar glucose can be used as the sole carbon source to grow the C. guilliermondii FTI 20037 cells for a subsequent xylose-to-xylitol bioconversion in wheat straw hemicellulosic hydrolysate. Moreover, they confirm the validity of using glucose as the sole carbon source for inoculum preparation in experiments aimed at xylitol bioproduction (9,(12)(13)15).…”

Hemicellulosic ethanol production by immobilized cells ofScheffersomyces stipitis: Effect of cell concentration and stirring

“…The SB was mixed with H 2 SO 4 (98% purity) at a ratio of 100 mg H 2 SO 4 / g of dry bagasse for 20 min at 121 C, using 10% substrate concentration. 11,12 After hydrolysis, the reaction mixture was cooled, recovered and was stored at 4 C. The hydrolysate was concentrated under a reduced pressure by a concentrator of 32L capacity at 70 C in order to obtain a xylose concentration of 30 g/L. This concentrated hydrolysate was subsequently detoxified following the method of Alves et al 13 to remove inhibitors generated during dilute acid hydrolysis.…”