title: Complete Growth Inhibition of Bacillus subtilis by Nisin-Producing Lactococci in Fermented Soybeans.
abstract: 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.
authors.affiliation: a Food Research Institute, Aichi Prefectural Government.
authors.forename: T
authors.initials: T
authors.lastname: Kato
authors.affiliation: b Marusan-Ai Co. Ltd.
authors.forename: K
authors.initials: K
authors.lastname: Maeda
authors.affiliation: c Faculty of Agriculture, Meijo University.
authors.forename: H
authors.initials: H
authors.lastname: Kasuya
authors.affiliation: d Graduate School of Bioagricultural Sciences, Nagoya University.
authors.forename: T
authors.initials: T
authors.lastname: Matsuda
keywords: Bacillus subtilis inhibition; bacteriocinogenic lactic acid bacteria; nisin; soybean miso fermentation