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Pretreatment is the requisite step for the bioconversion of lignocellulosics. Since most of the pretreatment strategies are cost/energy intensive and environmentally hazardous, there is a need for the development of an environment-friendly pretreatment process. An ionic liquid (IL) based pretreatment approach has recently emerged as the most appropriate one as it can be accomplished under ambient process conditions. However, IL-pretreated biomass needs extensive washing prior to enzymatic saccharification as the enzymes may be inhibited by the residual IL. This necessitated the exploration of IL-stable saccharification enzymes (cellulases). Current study aims at optimizing the bioprocess variables viz. carbon/nitrogen sources, medium pH and fermentation time, by using a Design of Experiments approach for achieving enhanced production of ionic liquid tolerant cellulase from a bacterial isolate Bacillus subtilis SV1. The cellulase production was increased by 1.41-fold as compared to that under unoptimized conditions. IL-stable cellulase was employed for saccharification of IL (1-ethyl-3-methylimidazolium methanesulfonate) pretreated pine needle biomass in a newly designed bioprocess named as "one pot consolidated bioprocess" (OPCB), and a saccharification efficiency of 65.9% was obtained. Consolidated bioprocesses, i.e., OPCB, offer numerous techno-economic advantages over conventional multistep processes, and may potentially pave the way for successful biorefining of biomass to biofuel, and other commercial products.

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

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