Conversion of Waste Agriculture Biomass to Bioethanol by Recombinant <i>Saccharomyces cerevisiae</i>

Abstract

Agricultural waste biomass has already been transferred to bioethanol and used as energy related products, although many issues such as efficiency and productivity still 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.

Effects of heating rate and heating up time to central biomass particles for bio-oil production

“…In terms of the cost, it is a least cost energy source and sometimes it has negative cost associated with its disposal in the rural area especially in the developing countries (McGowan, 1991;Kinoshita et al,1997). Thus the energy such as electricity and heat generation from biomass are considered the most lucrative opportunity for commercial exploitation and environmental protection, since the high value of electricity and heat (Van den Broek et al, 2000;Saleh et al, 2010).…”