自然界から分離した黄麹菌(Aspergillus oryzae)と醸造用黄麹菌の比較解析

概要

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Aspergillus oryzae is widely used to produce fermented food such as sake, soy sauce and miso in Japan. Since these fungi have been used for food fermentation for a long time, these economic strains for food fermentation are thought as "domesticated strains." The origin of these strains is thought to be a contaminant from natural environment. We isolated many A. oryzae like strains from field using the autoclaved rice as medium. Isolated strains were confirmed as A. oryzae by the genomic structure of aflatoxin homologous gene cluster. The amount of mycelium in rice koji prepared by isolated strains did not show the significant differences compared with those of commercial strains. The activities of enzymes such as α-amylase, glucoamylase, acid carboxypeptidase, acid protease and neutral protease in rice kojiprepared by isolated eight strains and commercial strains were analyzed. Some of the isolated strains showed the similar enzyme activities to those of the commercial strains. From these results, it is suggested that the present commercial A. oryzae strains originate from A. oryzaeliving in the natural environment.
2012-03-10