Bioconversion of Agricultural Waste to Ethanol by SSF Using Recombinant Cellulase fromClostridium thermocellum

Abstract

The effect of different pretreatment methods, temperature, and enzyme concentration on ethanol production from 8 lignocellulosic agrowaste by simultaneous saccharification and fermentation (SSF) using recombinant cellulase andSaccharomyces cerevisiaewere studied. Recombinant cellulase was isolated fromE. coliBL21 cells transformed with CtLic26A-Cel5-CBM11 full-length gene fromClostridium thermocellumand produced in both batch and fed-batch processes. The maximum cell OD and specific activity in batch mode were 1.6 and 1.91 U/mg, respectively, whereas in the fed-batch mode, maximum cell OD and specific activity were 3.8 and 3.5 U/mg, respectively, displaying a 2-fold increase. Eight substrates,Syzygium cumini(jamun),Azadirachta indica(neem),Saracens indica(asoka),bambusa dendrocalmus(bamboo),Populas nigra(poplar),Achnatherum hymenoides(wild grass),Eucalyptus marginata(eucalyptus), andMangifera indica(mango), were subjected to SSF. Of three pretreatments, acid, alkali, and steam explosion, acid pretreatmentSyzygium cumini(Jamun) at 30°C gave maximum ethanol yield of 1.42 g/L.