Monday, April 29, 2013
Exhibit Hall
Sugarcane bagasse can be considered as a good feedstock for the production of second-generation fuel ethanol. In our study, fungal strains were isolated from soil and rotten wood samples, collected from subtropical forests of National Natural Reserves in Guangxi and Yunnan provinces of China, on plates containing powder of filter paper as the sole carbon source. The selected fungal strains with higher avicelase activity in flask cultivation were screened for their ability to hydrolyze steam-pretreated sugarcane bagasse. Two fungal strains exhibited highest activity in hydrolyzing steam-exploded sugarcane bagasse. One of the two strains was identified as Penicillium oxalicum through the analysis of internal transcribed spacer (ITS) sequence of ribosomal RNA genes as well as by observing its morphological characteristics. The P. oxalicum strain was mutated thrice by treatment with 60Co–γ-ray irradiation. The selected mutant was further mutated by alternative treatment with ethyl methane sulfonate (EMS) and UV irradiation for two cycles. A mutant strain EU2106, which exhibited highest activity in hydrolyzing the filter paper, was obtained, and the culture conditions for cellulase production by the mutant were optimized. The mutant EU2106 produced 6.8 IU/ml of filter paper activity (FPA) in flask cultivation under optimized culture conditions. The cellulase produced by the mutant was found to be very effective in hydrolyzing pretreated sugarcane bagasse as well as in simultaneous saccharification and fermentation of sugarcane cellulose to ethanol using the thermotolerant yeast Saccharomyces cerevisiae, developed by our team.