Simultaneous saccharification and fermentation (SSF) of aqueous ammonia pretreated Saccharum spontaneum (wild sugarcane) for second generation ethanol production

Ethanol has drawn attention worldwide to be a true alternative of fossil fuel due to its renewable nature and economics. In the present study, we aimed to evaluate a cheaper and abundantly available wild species of sugarcane, Saccharum spontaneum, as the raw substrate for ethanol production under simultaneous saccharification and fermentation (SSF) conditions. The substrate was first pretreated with aqueous ammonia followed by enzymatic hydrolysis coupled with the fermentation of released sugars into ethanol by monoculture as well as mixed cultures of thermotolerant S. cerevisiae VS 3 and P. stipitis NCIM 3498. The cellulase enzyme used for saccharification was prepared from the culture supernatants of Aspergillus oryzae MTCC1846 grown under submerged fermentation conditions. A maximum of 0.85 +/- 0.07 IU/mL of filter paperase (FPase), 1.25 +/- 0.04 IU/mL of carboxy methyl cellulase (CMCase) and 55.56 +/- 0.52 IU/mL of xylanase activity was obtained after 7 days of incubation using delignified S. spontaneum as carbon source under submerged fermentation conditions. During SSF, P. stipitis, VS 3 and mixed culture showed ethanol production-15.73 +/- 0.44 g/l (productivity, 0.218 +/- 0.04 g/l/h), 14.22 +/- 0.15 g/l (productivity, 0.197 +/- 0.02 g/l/h) and 17.73 +/- 0.25 g/l (productivity, 0.246 +/- 0.02 g/l/h), respectively.