VARIANT YEAST, ITS BREEDING AND PRODUCTION OF FERMENTED FOOD USING THE SAME

摘要

PROBLEM TO BE SOLVED: To freely change the quantity of malic acid produced by a yeast and to diversify the production ratio between or among organic acids contained in fermented food, by destroying a gene encoding an isozyme of malic acid dehydrogenase or making it highly expressional. SOLUTION: The quantity of malic acid produced by a yeast is specifically reduced by partially or wholly deleting malic acid dehydrogenase of the yeast or by destroying a malid acid dehydrogenase gene. The quantity of malic acid produced by a yeast is specifically increased by increasing the malic acid dehydrogenase of the yeast or by amplifying a malic acid dehydrogenase gene. It is preferable to produce fermented food and liquor by employing variant yeasts in which the malic acid dehydrogenase gene (MDH2) is amplified or destroyed.