魚類食品におけるボツリヌスE型菌の発育と毒素産生に関する研究-III

Abstract

In order to establish the chemical nature of volatile acidic odors produced by Clostridium botulinum during growth, volatile fatty acids were determined by gas chormatography in the cultures of cooked meat broth inoculated with each strain of the six toxin-types. The results were as follows: 1. Acetic, propionic, n-butyric, iso-butyric, n-valeric, iso-valeric (iso-valeric and/or active α-methyl-butyric), and iso-caproic acids were identified in the cultures of type A, B and F. The branched acids except iso-caproic acid were deduced to be the metabolic products derived from some branched amino-acids by “Stickland reaction”. 2. Acetic, propionic, and n-butyric acids were identified in both the cultures of types Cβ and D. A high proportion of propionic acid among the resulting fatty acids suggests that these organisms appear to obtain some of their energy by propionic acid fermentation similar to that displayed by propionibacteria. 3. n-Butyric acid, in higher proportion, as well as acetic acid were identified in the cultures of type E, suggesting that this organism obtains most of its energy by butyric acid fermentation similar to that displayed by butyric acid bacteria. Further the chemical nature of the off-odor of foodstuffs contaminated with botulinal toxin was examined. An abnormally high proportion of n-butyric acid, being responsible for the “butyric” off-odor, was found in home-made “Izushi” of raw fish and rice cake, which had caused an episode of human type E botulism. Also a high proportion of propionic acid, as well as acetic and n-butyric acids were found in raw whale meat, which had caused an outbreak of type Cβ botulism in mink. Accordingly, the patterns of the volatile fatty acids presented by each type of Clostridium botulinum seem to be reflected in that of foodstuffs contaminated with respective type of the organisms.