Consolidated bioprocessing for biofuel‐ethanol production from pine needle biomass

Abstract

Lignocellulosic‐bioethanol‐fuel (LBF) technology faces challenges due to cost/energy intensive nature of lignocellulosic biomass (LB) pretreatment and saccharification. Ionic liquid (IL) based pretreatment of LB has recently emerged as an environmentally friendly approach. However, for saccharification of IL pretreated LB, IL stable enzymes must be used else the latter may be inhibited. Furthermore, availability of IL stable enzymes may help designing novel consolidated process by in situ coupling of IL mediated pretreatment of LB and enzymatic saccharification processes in a single vessel, that is, one pot consolidated bioprocess (OPCB). OPCB may potentially offer new avenues for technoeconomic feasibility of LBF. In this study, an OPCB was developed and optimized for the first time for bioethanol production from pine needle biomass (PNB) using in situ IL pretreatment and enzymatic saccharification in a single pot. Various process parameters, namely, biomass loading, reaction time, and cellulase/xylanase enzyme dose were optimized, and sugar yield of 1.88 g per five gram of PNB was obtained. The sugar hydrolysate obtained was subjected to ethanol fermentation using dual yeast culture, that is, Saccharomyces cerevisiae and Pichia stipitis. The maximum ethanol yield of 0.148 g/g PNB was obtained after 72 h of fermentation representing an efficiency of 41.39%. The study shows that consolidated processing of PNB may be an efficient, sustainable, and feasible approach for valorization of PNB for industrial production of second generation ethanol‐biofuel. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 546–552, 2018