腐敗細菌としてのFlavobacteriumの研究
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Flavobacterium are usually considered as putrefactive bacteria of fish and other food materials. They are gram negative, orange to yellow pigmented rods widely distributed in the fresh and marine water. This paper deals with an analytical investigation on the significance of genus Flavobacterium as the bacteria causing spoilage of food. The results obtained are summarized as follows: 1. Fifty six strains of Flavobacterium were isolated from fish materials. After the cultural characteristics of all isolates were tested in detail, taxonomical analysis was carried out. Only eleven strains were classified into species according to the key of Bergey's manual (1948), but others could not be identified because of their atypicality. In our collection, the author found three strains characterized for their urease activity. Especially Strain S 30 (one of them) rapidly produced large amount of urease, therefore this strain was named Flavobacterium Urea Nov SP. 2. Deterioration of texture and appearance in the food samples which were preserved at 27℃ after single inoculation of each strain were observed. Fish and fish products were easily attacked by many species of the genus, but in general the bacterial decomposition on fish meat was rather. weak comparing with Pseudomonas. Volatile Nitrogen was gradually produced during the course of the putrefaction by the inoculated bacteria, but the NH_3-N increase was slow in time and of less amount than the case of Pseudomonas. 3. Susceptibility to chemical agent antibiotics: Flavobacterium was rather resistant to various antibiotics, such as aureomycin, chloromycetin, streptomycin and penicillin. Only 57 % of strains were inhibited their growth at the concentration of 50 mcg/ml of streptomycin. Eight strains (13.6 %) were observed their growth in medium containing same concentration of aureomycin. Chemical preservatives. All strains were also resistant to several preservatives such as nitrofurazone, dehydroacetic acid and sorbic acid comparing with the case of Enterobacteriaceae. 4. Heat resistance, Psychrophilic strains. Flavobacterium was rather sensitive to heat shock. All strains were completely sterilized during pasteurisation process. Low temperature growth (at 4℃) was observed in 21 strains. 5. NaCl. and Sugar tolerance Although the normal growth was observed in medium containing 2 % NaCl, 88 % of the strains were inhibited their growth in 7 % NaCl. And there were no strains tolerated at the concentration of 10 % NaCl. The organismus was highly tolerant against sugar. Even in 50 % sugar medium, the growth was observed in 12 % of the tested bacteria.
- 千葉大学の論文
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- 腐敗細菌としてのFlavobacteriumの研究