Fed-batch cultivation of Mucor indicus in dilute-acid lignocellulosic hydro-lyzate for ethanol production

摘要

Mucor indicus fermented dilute-acid lignocellulosic hydrolyzates to ethanol in fed-batch cultivation with complete hexose utilization and partial uptake of xylose.The fungus was tolerant to the inhibitors present in the hydrolyzates.It grew in media containing furfural (1 g/l),hydroxymethylfurfural (1 g/l),vanillin (1 g/l),or acetic acid (7 g/l),but did not germinate directly in the hydrolyzate.However,with fed-batch methodology,after initial growth of M.indicus in 500 ml enzymatic wheat hydrolyzate,lignocellulosic hydrolyzate was fermented with feeding rates 55 and 100 ml/h.The fungus consumed more than 46% of the initial xylose,while less than half of this xylose was excreted in the form of xylitol.The ethanol yield was 0.43 g/g total consumed sugar,and reached the maximum concentration of 19.6 g ethanol/l at the end of feeding phase.Filamentous growth,which is regarded as the main obstacle to large-scale cultivation of M.indicus,was avoided in the fed-batch experiments.