초록
<P><B>Abstract</B></P><P><B>Aims: </B> To isolate thermotolerant <I>Saccharomyces cerevisiae</I> with high‐energy‐pulse‐electron (HEPE) beam, to optimize the mutation strain fermentation conditions for ethanol production and to conduct a preliminary investigation into the thermotolerant mechanisms.</P><P><B>Methods and Results: </B> After HEPE beam radiation, the thermotolerant <I>S.？cerevisiae</I> strain Y43 was obtained at 45°C. Moreover, the fermentation conditions of mutant Y43 were optimized by L3<SUP>3</SUP> orthogonal experiment. The optimal glucose content and initial pH for fermentation were 20% g l<SUP>−1</SUP> and 4·5, respectively; peptone content was the most neglected important factor. Under this condition, ethanol production of Y43 was 83·1 g l<SUP>−1</SUP> after fermentation for 48 h at 43°C, and ethanol yield was 0·42 g g<SUP>−1</SUP>, which was about 81·5% of the theoretical yield. The results also showed that the trehalose content and the expression of the genes <I>MSN2</I>, <I>SSA3</I> and <I>TPS1</I> in Y43 were higher than those in the original strain (YE0) under the same stress conditions.</P><P><B>Conclusions: </B> A genetically stable mutant strain with high ethanol yield under heat stress was obtained using HEPE. This mutant may be a suitable candidate for the industrial‐scale ethanol production.</P><P><B>Significance and Impact of the Study: </B> High‐energy‐pulse‐electron radiation is a new efficient technology in breeding micro‐organisms. The mutant obtained in this work has the advantages in industrial ethanol production under thermostress.</P>