초록
<P><B>Abstract</B></P><P>The development of a yeast strain that converts raw starch to ethanol in one step (called Consolidated Bioprocessing, CBP) could significantly reduce the commercial costs of starch‐based bioethanol. An efficient amylolytic <I>Saccharomyces cerevisiae</I> strain suitable for industrial bioethanol production was developed in this study. Codon‐optimized variants of the <I>Thermomyces lanuginosus</I> glucoamylase (<I>TLG1</I>) and <I>Saccharomycopsis fibuligera</I> α‐amylase (<I>SFA1</I>) genes were δ‐integrated into two <I>S. cerevisiae</I> yeast with promising industrial traits, i.e., strains M2n and MEL2. The recombinant M2n[TLG1‐SFA1] and MEL2[TLG1‐SFA1] yeast displayed high enzyme activities on soluble and raw starch (up to 8118 and 4461 nkat/g dry cell weight, respectively) and produced about 64 g/L ethanol from 200 g/L raw corn starch in a bioreactor, corresponding to 55% of the theoretical maximum ethanol yield (g of ethanol/g of available glucose equivalent). Their starch‐to‐ethanol conversion efficiencies were even higher on natural sorghum and triticale substrates (62 and 73% of the theoretical yield, respectively). This is the first report of direct ethanol production from natural starchy substrates (without any pre‐treatment or commercial enzyme addition) using industrial yeast strains co‐secreting both a glucoamylase and α‐amylase. Biotechnol. Bioeng. 2015;112: 1751–1760. © 2015 Wiley Periodicals, Inc.</P>