A mutant that is a high malic acid producer (M7-14) was isolated from among cycloheximideresistant mutants of Kyokai 7 yeast (K-7).In a small scale sake brewing test using this strain, the sake produced had a sweet taste with a low alcohol concentration;sake meter -36 and 12% of ethanol.The production of malic acid by M7-14 was 2.8 times that of K-7.When sodium azide, which inhibits the tricarboxylic acid (TCA) metabolic cycle, was added to the M7-14 culture, malic acid production fell to half that of the same culture without sodium azide.From this result, it was proposed that a pathway other than the TCA cycle might be involved in malic acid production in M7-14.The mechanism of malic acid production by M7-14 was investigated by measurement of the enzyme activities in the TCA cycle and glyoxylic acid cycle.It was found that the activities of malate dehydrogenase and isocitrate lyase in M7-14 were higher than those of K-7.Thus, it is clear that the glyoxylic acid cycle is responsible for the high production of malic acid and succinic acid by M7-14.