Open AccessNew Approach of Highly Efficient Fermentation Process for Bioethanol using Xylose as Agriculture Residues
Author(s) -
Abu Saleh Ahmed,
Shizuo Watanabe,
Sinin Hamdan,
Tsutomu Kodaki,
Keisuke Makino
Publication year - 2017
Publication title -
asean journal on science and technology for development/asean journal on science and technology for development
Language(s) - English
Resource type - Journals
eISSN - 2224-9028
pISSN - 0217-5460
DOI - 10.29037/ajstd.299
Subject(s) - pichia stipitis , xylose , xylitol , fermentation , ethanol fuel , xylose metabolism , biochemistry , biofuel , chemistry , food science , metabolic engineering , biomass (ecology) , enzyme , biology , microbiology and biotechnology , agronomy
Agricultural waste biomass has already been transferred to bioethanol and used as energy related products, although many issues such as efficiency and productivity still exist to be overcome. In this study, the protein engineering was applied to generate enzymes with completely reversed coenzyme specificity and developed recombinant yeasts containing those engineered enzymes for construction of an efficient biomass-ethanol conversion system. Recombinant yeasts were constructed with the genes encoding a wild type xylose reductase (XR) and the protein engineered xylitol dehydrogenase (XDH) (with NADP) of Pichia stipitis. These recombinant yeasts were characterized based on the enzyme activity and fermentation ability of xylose to ethanol. The protein engineered enzymes were expressed significantly in Saccharomyces cerevisiae as judged by the enzyme activity in vitro. Ethanol fermentation was measured in batch culture under anaerobic conditions. The significant enhancement was found in Y-ARS strain, in which NADP+-dependent XDH was expressed; 85% decrease of unfavorable xylitol excretion with 26% increased ethanol production, when compared with the reference strain expressing the wild–type XDH.