초록
<P><B>Background</B></P><P>The optimization of industrial bioethanol production will depend on the rational design and manipulation of industrial strains to improve their robustness against the many stress factors affecting their performance during very high gravity (VHG) or lignocellulosic fermentations. In this study, a set of <I>Saccharomyces cerevisiae </I>genes found, through genome-wide screenings, to confer resistance to the simultaneous presence of different relevant stresses were identified as required for maximal fermentation performance under industrial conditions.</P><P><B>Results</B></P><P>Chemogenomics data were used to identify eight genes whose expression confers simultaneous resistance to high concentrations of glucose, acetic acid and ethanol, chemical stresses relevant for VHG fermentations; and eleven genes conferring simultaneous resistance to stresses relevant during lignocellulosic fermentations. These eleven genes were identified based on two different sets: one with five genes granting simultaneous resistance to ethanol, acetic acid and furfural, and the other with six genes providing simultaneous resistance to ethanol, acetic acid and vanillin. The expression of <I>Bud31 </I>and <I>Hpr1 </I>was found to lead to the increase of both ethanol yield and fermentation rate, while <I>Pho85</I>, <I>Vrp1 </I>and <I>Ygl024w </I>expression is required for maximal ethanol production in VHG fermentations. Five genes, <I>Erg2</I>, <I>Prs3</I>, <I>Rav1</I>, <I>Rpb4 </I>and <I>Vma8</I>, were found to contribute to the maintenance of cell viability in wheat straw hydrolysate and/or the maximal fermentation rate of this substrate.</P><P><B>Conclusions</B></P><P>The identified genes stand as preferential targets for genetic engineering manipulation in order to generate more robust industrial strains, able to cope with the most significant fermentation stresses and, thus, to increase ethanol production rate and final ethanol titers.</P>