Simultaneous bioconversion of rice straw into an intermediate product using ionic liquid and native extracellular hydrolytic enzyme from indigenous actinomycetes

Abstract

Bioethanol production technology using lignocellulosic substrates has become a focus to overcome the limited supply of fossil fuels in the current century. Simultaneous saccharification requires an understanding of suitable efficient procedures in bioconversion row material into fermented sugar. In this study, the effect of pre-treated rice straws using ionic liquid on enzymatic saccharification by isolated actinomycetes was investigated. Ionic liquid to rice straw in a ratio (IL/RS) was set up 0 to 3 (g/g), and the remaining of the ionic liquids in pre-treated biomass was examined for their effect on the hydrolytic enzyme activity of the actinomycetes. Three actinomycetes were isolated from decomposed rice straw and were purified and screened for their cellulolytic and xylanolytic activity; one strain, namely ActRS-4, was selected as an optimum isolate for further hydrolysis examination. Both cellulase and xylanase activity exhibit a peak at a ratio IL/RS of 1 (g/g), the activity was 27.72 and 66.16 U/ml, respectively. The highest yield of sugar was also achieved at this IL/RS ratio for 8 days of incubation. The pretreatment indicates that it could promote an increase in the yield of glucose and xylose by 28% and 37% respectively. This study was promising to develop a one-pot conversion of lignocellulosic biomass into bioethanol using the biological process.