Bioconversion of rice straw by synergistic effect of in-house produced ligno-hemicellulolytic enzymes for enhanced bioethanol production

Abstract

In the present work attempts have been made to mimic the natural system of biomass delignification using laccase from Myrothecium verrucaria ITCC-8447 and synergistic effect of cellulase and xylanase from Schizophyllum commune NAIMCC-F-03379 and Aspergillus oryzae ITCC-8571 respectively for enhanced saccharification and subsequent bioethanol production. The laccase mediated pretreatment resulted in 6.7% delignification of rice straw (RS). The structural analysis of enzymatic pretreated RS using XRD and FTIR suggested high crystallinity index (CrI) and improved accessibility of cellulose and hemicelluloses as compared to untreated RS. The single step simultaneous delignification, saccharification and fermentation (SDSF) of RS using partially purified in-house enzyme cocktail with Saccharomyces cerevisiae MTCC-173 resulted in sugar yield of 26.7 ± 0.2 g/L with an experimental ethanol yield of 6.47 ± 0.16 g/L which is comparable to maximum sugar and ethanol yield of 31.2 ± 0.7 g/L and 7.34 ± 0.39 g/L respectively using commercial enzyme cocktail with S. cerevisiae MTCC-173. The SDSF was obtained as a suitable single step process for the ethanol production from RS.