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B. coagulans is known as flat-sour bacteria. It is very important to control spores of B. coagulans for canned foods, retort pouched foods and etc. The present study was undertaken to compare the inhibitive effect of organic acids on the germination of spores of B. coagulans. The following results were obtained. (1) The most effective organic acid for inhibition of the spore germination was citric acid as compared with acetic acid, lactic acid and malic acid. (2) Organic acids used inhibited the germination of the spores, and were more effective on heat injured spores than non-heated ones. But organic acids did not have any bactericidal action because after heat treatment in acidic condition, spores were able to germinate when transferred into medium adjusted at pH 7.0

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A total of 173 soil samples were collected from 16 rivers to survey for Clostridium botulinum in Miyazaki Prefecture from February to July, 1986. Twenty-one among 173 samples (12.1%) showed positive for this organism. In further analysis, 18 of the cultures containing the toxin were typed by the neutralization technique; 10 were type C, 6 type D, and 2 type E. The distribution of the toxin types of C. botulinum in Miyazaki Prefecture resembles that in the central regions of Japan, but not that in Hokkaido.

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Mycophagy and fungal transmission by Tyrophagus putrescentiae (Schrank) a cheese mite were investigated with a total 32 species of 24 genera of fungi of food-borne and air-borne, as well as an isolate from tatami-mats. The abillity to transmit fungal spore was estimated both externally and internally. Reproduction of the cheese mite was observed on cultures of 29 fungal species. In cultures of Acremonium sp., Phoma sp. and Penicillium frequentans, the mite of population increased in number by more 100 times of the initial in 30 days incubation at 25°C; while Aspergillus awamori, Chaetomiun sp. or Eurotium herbariorum did not contribute to multiplication of the cheese mite. The role of the cheese mite in transmitting fungal spores was also diverse; generally, such small-spored fungi as Aspergillus, Penicillium and Phoma were re-isolated from the body surfaces and inside of the cheese mite after contamination, but only a few species of large-spored fungi were detectable both externally and internally on the mite bodies. Tyrophagus putrescentiae was apparently fungivorous but higher incidences of viable spore-containing feces of the cheese mite were found in small-spored fungi rather than in large-spored fungi.
Effects of the mite contamination on the growth and aflatoxin production by Aspergillus flavus was also studied. The growth and aflatoxin production by A. flavus were less in a mixed culture with the cheese mite than in pure culture. Thus, the cheese mite did not significantly enhance aflatoxin B₁ production on the corn substrate.

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[in Japanese]

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