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

Author(s):  
Débora Danielle Virgínio da Silva ◽  
Maria das Graças de Almeida Felipe ◽  
Ismael Maciel de Mancilha ◽  
Sílvio Silvério da Silva
2002 ◽  
Vol 57 (1-2) ◽  
pp. 109-112 ◽  
Author(s):  
Walter Carvalho ◽  
Silvio S. Silva ◽  
Michele Vitolo ◽  
Maria G. A. Felipe ◽  
Ismael M. Mancilha

Candida guilliermondii cells were immobilized in Ca-alginate beads and used for xylitol production from concentrated sugarcane bagasse hydrolysate during five successive fermentation batches, each lasting 48 hours. The bioconversion efficiency of 53.2%, the productivity of 0.50 g/l × h and the final xylitol concentration of 23.8 g/l obtained in the first batch increased to 61.5%, 0.59 g/l × h and 28.4 g/l, respectively, in the other four batches (mean values), with variation coefficients of up to 2.3%.


2007 ◽  
Vol 50 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Débora Danielle Virgínio da Silva ◽  
Ismael Maciel de Mancilha ◽  
Silvio Silvério da Silva ◽  
Maria das Graças de Almeida Felipe

The effect of glucose on xylose-to-xylitol bioconversion by Candida guilliermondii was examined by adding it to sugarcane bagasse hydrolysate medium to obtain different glucose:xylose ratios (1:25, 1:12, 1:5 and 1:2.5). Under experimental conditions, increasing glucose:xylose ratio improved the assimilation of the xylose present in the hydrolysate by yeast, resulting in biomass increase, and in the formation of xylitol and glycerol/ethanol by-products. Maximum values of xylitol yield (0.59 g g-1) and volumetric productivity (0.53 g l-1.h-1) were obtained with glucose:xylose ratio of 1:5, resulting in the higher conversion efficiency (64.3%).


2000 ◽  
Vol 55 (3-4) ◽  
pp. 213-217 ◽  
Author(s):  
Walter de Carvalho ◽  
Silvio Silvério da Silva ◽  
Michele Vitolo ◽  
Ismael Maciel de Mancilha

Abstract In this study we used the yeast Candida guilliermondii FTI 20037 immobilized by entrapment in Ca-alginate beads (2 .5 -3 mm diameter) for xylitol production from concentrated sugarcane bagasse hemicellulosic hydrolysate in a repeated batch system. The fermentation runs were carried out in 125- and 250-ml Erlenmeyer flasks placed in an orbital shaker at 30 °C and 200 rpm during 72 h, keeping constant the proportion between work volume and flask total volume. According to the results, cell viability was substantially high (98%) in all fermentative cycles. The values of parameters xylitol yield and volumetric productivity increased significantly with the reutilization of the immobilized biocatalysts. The highest values of xylitol final concentration (11.05 g/1), yield factor (0.47 gig) and volumetric productivity (0.22 g/lh) were obtained in 250-ml Erlenmeyer flasks containing 80 ml of medium plus 20 mi of immobilized biocatalysts. The support used in this study (Ca-alginate) presented stability in the experimental conditions used. The results show that the use of immobilized cells is a promising approach for increasing the xylitol production rates.


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