Transcriptome Analysis of Sake Yeast in Co-Culture with <i>kuratsuki Kocuria</i>

<i>Kuratsuki</i> bacteria enter the sake production process and affect the flavor and taste of sake. This study compared gene expression in the sake yeast <i>Saccharomyces cerevisiae</i> in co-culture with <i>kuratsuki Kocuria</i> to that in monoculture. Among the 5922 genes of <i>S. cerevisiae</i>, 71 genes were upregulated more than 2-fold, and 61 genes were downregulated less than 0.5-fold in co-culture with <i>kuratsuki Kocuria</i>. Among the stress-induced genes, fourteen were upregulated, and six were downregulated. Among the fourteen upregulated genes, six were induced in response to replication stress. Although the G1 cyclin gene <i>CLN3</i> was upregulated by more than 2-fold, eight genes that were induced in response to meiosis and/or sporulation were also upregulated. Fourteen metabolism-related genes, for example, the glyceraldehyde-3-phosphate dehydrogenase genes <i>TDH1</i>, <i>TDH2</i>, and <i>TDH3</i>, were downregulated by less than 0.5-fold in co-culture with <i>kuratsuki Kocuria</i>. The gene expression patterns of <i>S. cerevisiae</i> co-cultured with <i>kuratsuki Kocuria</i> differed from those co-cultured with lactic acid bacteria. Therefore, <i>S. cerevisiae</i> responded differently to different bacterial species. This strongly suggests that <i>kuratsuki</i> bacteria affect gene expression in sake yeast, thereby affecting the flavor and taste of sake.