期刊
JOURNAL OF GENERAL AND APPLIED MICROBIOLOGY
卷 60, 期 5, 页码 198-206出版社
MICROBIOL RES FOUNDATION
DOI: 10.2323/jgam.60.198
关键词
bioethanol; cellulose; coexpression; consolidated bioprocessing; endoglucanase; beta-glucosidase
资金
- Science and Technology Planning Project of Guangdong Province [2012B020311005]
- Program for New Century Excellent Talents in University [NCET-05-0745]
- Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China
Direct ethanol fermentation from amorphous cellulose was achieved using an engineered industrial Saccharomyces cerevisiae strain. Two cellulase genes endoglucanase (eg3) and beta-glucosidase (bgl1) were obtained from Trichoderma viride and integrated into the genome of S. cerevisiae. These two cellulases could be constitutively coexpressed and secreted by the recombinant strain S. cerevisiae-eb. The enzyme activities were analyzed in the culture supernatants, with the highest endoglucanase activity of 2.34 units/ml and beta-glucosidase activity of 0.95 units/ml. The effects of pH, temperature and metal ions on enzyme activities were analyzed. The coexpression strain S. cerevisiae-eb could grow in carboxymethyl cellulose (CMC) and utilize it as the single carbon source. The 20 g/L CMC as a model substrate of amorphous cellulose was used in fermentation. The ethanol production reached 4.63 g/L in 24 h, with the conversion ratio of 64.2% compared with the theoretical concentration. This study demonstrated that the engineered industrial strain S. cerevisiae-eb could convert amorphous cellulose to ethanol simultaneously and achieve consolidated bioprocessing (CBP) directly.
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