Enhanced Cellulosic Ethanol Production from Mild-Alkali Pretreated Rice Straw in SSF Using Clavispora NRRL Y-50464

摘要

The current investigation reports cellulosic ethanol productions from rice straw pretreated by mild alkali- and dilute acid-pretreatment methods applying a native p-glucosidase producing yeast strain, Clavispora NRRL Y-50464 by SSF. Peak ethanol yields of 21.2, 25.7 and 24.3 g L-1 were observed with mild alkali pretreated rice straw at 10, 15, and 20% of solids loading within 60 h incubation period. While acid pretreated rice straw produced maximum ethanol yields up to 12.5, 16.8 and 12.4 g L-1 at similar solids loading levels. The ethanol conversion efficiency of rice straw pre-treated by mild alkali method (79.2, 64.0 and 45.4%) was significantly higher than that pre-treated by dilute acid method (58.9, 52.7 and 29.2%) at all solids loading levels. Y-50464 is an extremely fast growing ethanologenic yeast strain and completed its fermentation on 5% glucose within 18 h. In addition to glucose, albeit slow, Y-50464 strain also utilizes xylose (upto 5%) for its metabolic growth. The efficient cellulosic ethanol conversion from mild alkali pretreated rice straw at high solid loadings with no additional supplementation of p-glucosidase and short SSF process times suggests a promising potential of Y-50464 yeast strain for cost-efficient renewable biofuel production towards an economic consolidated bio processing.