中国生物工程杂志

Abstract The balance computation and metabolism analysis of carbon in xylose/glucose fermentation by Pichia stipitis was studied. A 400 h continuous chemostat culture was divided into 4 phases by adding different sugar concentration during each phase. By controlling temperature of （35±1）℃ and aeration of 100～150mL/min and stirring speed of 250～300 r/min, one steady state was established during each phase. The carbon recovery ratios of the four steady states were 118.0%, 105.6%, 113.5% and 94.7 %, respectively. By analyzing of metabolic effluence of carbon, it was found that approximately 50.0 % carbon from glucose and xylose was mainly turned into ethanol, while carbon was secondly emitted as CO2 and thirdly charged into yeast cells. Xylitol concentration was correlative with substrate xylose concentration. Aeration of 100～150mL/min was appropriate to continuous fermentation with mixture substrate of 30.0 g/L xylose and 30.0 g/L glucose .