In regard to melezitose assimilation of industrial yeast, we focused attention on MAL genes and attempted to elucidate them by a molecular biological approach. When we cultured maltose or melezitose as a carbon source with the brewers yeast except the sake yeast, expression of the AGT1, MALx1, MAL13 and MALx2 were detected. When we cultured maltose as a carbon source with the sake yeast, the expression of AGT1 and MALx2 were detected, but the expression of MALx1 and MAL13 were feeble. These sake yeast differed from other yeast as follows:1) the base sequence of MAL13 differed greatly; 2) chromosome VII did not have AGT1, and MAL13 and MALx1 were adjacent on the chromosome IV; 3) there were few MALx1 homology arrangements.
