The influence of hexoses addition on the fermentation of d-xylose in Debaryomyces hansenii under continuous cultivation

Improvement of biotechnological xylitol production by glucose during cultive of Candida guilliermondii in sugarcane bagasse hydrolysate

“…In this case, a reduction of fermentation time and an increase of 19% in xylitol yield (0.50 g g -1 ) in relation to the medium without glucose were observed. This improvement was also observed during the cultivation of D. hansenii in synthetic medium (Tavares et al 2000). These authors observed an increase of 30% in xylitol yield (Y P/S = 0.56 g g -1 ), employing a glucose:xylose ratio of 1:10 in relation to the medium without glucose.…”

“…This behaviour could be explained by the fact that the enzymes required for glucose metabolism are constitutive enzymes or enzymes full time required by the cells and maintained in constant levels (Dawes and Sutherland 1992). Simultaneous use of xylose and glucose was observed by Tavares et al (2000) during cultivation of D. hansenii in synthetic medium; however, a catabolic repression of xylose assimilation by glucose occurred when increasing amounts of glucose (glucose:xylose =1:10) were added to the medium. In contrast, many works relate sequential sugar utilization, with preferential glucose assimilation in fermentation of sugar mixture (Preziosi-Belloy et al 1997;Oh and Kim 1998;Walther et al 2001).…”

“…The general pattern observed for yeast batch cultivation on sugar mixtures is the inhibition or retardation of xylose utilization by the presence of glucose in the growth media. The presence of this readily metabolize hexose can induce regulatory problems due to an interaction between the different sugars metabolisms resulting in poor xylose assimilation, and hence greatly influence xylitol yield and productivity (Tavares et al 2000). According to Walker (1998), the presence of glucose in hemicellulosic hydrolysate can inhibit xylose metabolism by repression or inactivation of catabolic enzymes and transport system of this pentose.…”

Simultaneous lactic acid and xylitol production from vine trimming wastes

“…Similar findings were observed by Yahashi et al 30 When working with high glucose concentration detected significant amounts of glycerol and ribitol as subproducts of fermentation. Similarly, Tavares et al 21 found in the fermentation broth low glycerol concentrations related when using high glucose concentrations and D hansenii.…”

A model of xylitol production by the yeast Candida mogii

“…Supplementation with glucose in a xylose fermentation can thus be used to enhance the yield of xylitol. The presence of small amounts of glucose in the medium has indeed improved xylitol yield from xylose in yeast fermentations [2][3][4]; however, high concentrations of glucose are known to inhibit xylose transport into the cell [5] and repress induction of relevant enzymes by xylose [6,7].…”