The enhancement of ammonia pretreatment on the fermentation of rice straw hydrolysate to xylitol

In xylitol fermentation from rice straw hydrolysate by Candida tropicalis As2.1776, ammonia steeping was employed to pretreat the rice straw. Experimental results showed that the content of toxic compounds created in the hydrolysis process, such as acetic acid and phenolic compounds, was greatly reduced and the fermentation of the hydrolysate was enhanced. Xylitol fermentation was investigated in flasks and a 2-L bioreactor, respectively. The xylitol yield factor and volumetric productivity were 0.746 g/g and 0.686 g/(L.h) in the lab-flask fermentation, respectively. The corresponding results conducted in bioreactor fermentation were 0.689 g/g and 0.697 g/(L.h), respectively.