Separate and simultaneous saccharification and fermentation of a pretreated mixture of lignocellulosic biomass for ethanol production

Abstract

ABSTRACTDepleting fossil fuel resources and greenhouse gas emissions have become global concerns. To address this issue, a new strategy was adopted in the present study: to utilize a mixture of lignocellulosics for bioethanol production. Renewable fuel demand is addressed in the present study by initial processing of various combinations of the lignocellulosic substrates Ricinus communis (RC), Lantana camara (LC), Saccharum officinarum tops (SCT), Saccharum spontaneum (KG), Ananas comosus leaf wastes (PA) and Bambusa bambos (BB) with laccase to disassemble recalcitrant lignin from holocellulose and ease the enzymatic hydrolysis for reducing sugar yield. An attempt on separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) has been made to explore the possibilities of enhanced ethanol productivity using Saccharomyces cerevisiae. Central composite design (CCD) based response surface methodology (RSM) was employed to infer the optimum conditions to conduct SSF and SHF. It was found that under optimized conditions, SSF resulted in higher ethanol productivity (1.396 g/L/h) after 30 h at lower cellulase loading (80 U/g) than SHF (0.929 g/L/h) after 27.33 h at higher cellulase loading (132.9 U/g). The increase in ethanol concentration was 1.64 folds, suggestive of the advantage of SSF (41.9 g/L) over SHF (25.40 g/L).