サケ科魚類の腸内細菌叢に関する研究. V, 溯河魚の腸内細菌叢

日本水産学会

日本水産学会誌

Ten adult pink salmon (Oncorhynchus gorbuscha) caught at the mouth of a river for collecting their eggs and reared about 3 months in fresh water without feeding, 20 anadromous chum salmon (Oncorhynchus keta) caught for the same purpose, and 10 cultured masu salmon (Oncorhynchus masou) which had reached their maturity were used as test samples. The pink and chum salmon were provided by the Oshima Branch of the Hokkaido Salmon Hatchery and the masu salmon, by the Mori Branch of the Hokkaido Fish Hatchery. Viable counts were determined in the intestinal slime of these salmon. About 370 strains were isolated from the above samples. The composition of the microflora was determined according to the scheme of SHEWAN et al. (1960). The results are summarized as follows: 1) The number of microorganisms in the intestinal slime of the anadromous pink and chum salmon ranged from 10^2 to 10^8 per gram. In the mature masu salmon, it was less, ranging from nil to 10^5 per gram. 2) The predominant genera in the intestinal slime of the anadromous pink and chum salmon were the Vibrio, Pseudomonas, and Aeromonas. All of the Vibrio were of the marine or halophilic type, the Pseudomonas were of the halophilic and terrestrial type, and most of the Aeromonas were of the terrestrial type. 3) The Aeromonas were predominant in the intestinal microflora of the mature masu salmon cultured in fresh water.

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