Complete Growth Inhibition of Bacillus subtilis by Nisin-Producing Lactococci in Fermented Soybeans

概要

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The growth inhibition by nisin-producing lactococci against Bacillus subtilis and its application to soybean miso fermentation were investigated. Lactococcus lactis subsp. lactis IFO12007 (nisin-producing, salt-intolerant) rapidly proliferated to more than 10^9 cells/g in cooked soybeans without any excessive pH decrease. In spite of the mild decrease in pH, the growth of B. subtilis was completely inhibited ; no living cells were detected in a soybean sample inoculated with 10^6 cells/g and incubated for 24 to 72 h. This Lc. lactis was applied to soybean miso fermentation as a starter culture. It produced high nisin activity (1.28×10^5 AU/g) in cooked soybean, resulting in the complete growth inhibition of B. subtilis, which had been inoculated at the beginning of the koji fermentation, throughout the process of miso production. Over-acidification, which is undesirable for miso quality, was successfully prevented simply by adding salt which killed the salt-intolerant Lc. lactis. Furthermore, the nisin activity in miso disappeared with aging.
社団法人日本農芸化学会の論文
1999-04-23