The bottom fermenting yeast Saccharomyces pastorianus (formerly Saccharomyces carlsbergensis) has one ATF1 gene and a homologous gene called Lg-ATF1 which encode alcohol acetyltransferases. Southern blot analysis of chromosomes separated by pulsed-held gel electrophoresis in a variety of bottom fermenting yeasts showed that in most of the yeasts analyzed, the ATF1 gene is located on the 1000- and 1050-kb chromosomes or only on the 1050-kb chromosome, while the Lg-ATF1 gene is located on the 850-kb chromosome. Acetate ester synthesis in a bottom fermenting yeast was found to be reduced by aeration or the addition of an unsaturated fatty acid. The enzyme activities involved in the synthesis of acetate esters decreased under these conditions. Experiments using ATF-lacZ fusion genes showed that the transcription of the ATF1 and Lg-ATF1 genes is co-regulated and is repressed by aeration or the addition of an unsaturated fatty acid. These findings suggest that the reduction in acetate ester synthesis observed in the bottom fermenting yeast was due to a reduction in enzyme synthesis resulting from transcriptional repression of the ATF1 and Lg-ATF1 genes.