Development of tailored bioprocess for pretreatment and saccharification of corn stalk into bioethanol using hydrolytic enzymes cocktail and fermentative yeasts

Abstract

Agriculture waste residue (corn stalk), a rich source of reducing sugars explored in the present study for the production of bioethanol using hydrolytic enzymes and fermenting yeast cocktails. Corn stalk pulp was biologically pretreated using hydrolytic enzymes cocktail of ligninase, cellulase and xylanase produced from Bacillus sp. PHS-05, Bacillus subtilis CP-S66 and Bacillus safensis XP-S7 with 2.34 ± 0.28 U/ml, 6.89 ± 0.36 U/ml and 11.9 ± 0.22 U/ml enzyme activities respectively. This biological pretreatment of corn stalk pulp resulted into 51.41 ± 0.34 % removal of lignin and 77.43 ± 2.44 % extraction of reducing sugar (C5 & C6). The changes occur in corn stalk pulp after enzymatic saccharification was confirmed by Fourier-Transform Infrared Spectroscopy (FTIR). Corn stalk sugar hydrolysate was co-fermented into 0.77 ± 0.06 g/g bioethanol with yield of 26.6 ± 0.46 g/kg of biomass, using Kluyveromyces marxianus MTCC 1498 and Saccharomyces cerevisiae. Further, purity (94.27 %) and volumetric productivity (0.20 ± 0.04 g/L/h) of bioethanol was confirmed using Gas Chromatography-Mass Spectrometry (GC-MS). Present findings provide valuable insight to obtain second generation biofuels to solve energy crisis, and environmental problems besides boosting socioeconomic prosperity through sustainable management of agro-residues.