Microorganism and Pretreatment Effect on Lignocellulosic Bioethanol Production

Abstract

The effects of pretreatments applied to raw materials and microorganism selection inlignocellulosic bioethanol production were investigated. It has been found that the yield ofenzymatic pretreatment process applied after the chemical pretreatment is about 4 times higherthan that only chemical. Enzymatic pretreatment used process yield is 3.5 times higher than thatchemical pretreatment. When the microorganism ethanol production yield values ofSaccharomyces cerevisiae and Pichia stipitis were examined, it was found that S.cerevisiae wassuperior to P.stipitis in chemical pretreated reactors (about 1.7 times higher) while P. stipitis’yield was higher about 1.2 times in enzymatic pretreated reactors. When the reactors whichhave been pretreated with both chemical and enzymatic hydrolysis and P. stipitis andS. cerevisiae used separately were examined, it was observed that there was not a greatdifference in terms of ethanol production yield. C. thermocellum’s ethanol yield was foundabout 3 times lower than the S. cerevisiae and P. stipitis. According to the obtained data, it wasseen that S. cerevisiae could produce ethanol with higher efficiency than P. stipitis. At the sametime, the difficulty of C. thermocellum’s production conditions, high energy demand and highrisk of contamination, and low ethanol production yield, it is thought that it can only be used inthe research phase for now. But in particular, by investigating extracellular cellulase enzymesystem of C. thermocellum, genetic modifications are predicted to play an important role in thefuture in the second generation bioethanol production process.