| Summary: | In order to ascertain the origin of free volatile fatty acids (FVFAs) which were detected previously in the stomach fluid of porpoises, the acid composition in the culture solutions of the microorganisms isolated from the porpoises was studied by GLC. The microorganisms used for the experiment were 2 strains of bacteria, Corynebacterium sp. (gram positive) and Vibrio sp. (gram negative), and a strain of Candida tropicalis-like yeast. Incubations were made in peptone-glucose medium (1) by changing growth temperature, pH value and NaCl concentration. The results obtained are as follows. 1) In all the microorganisms acetic, propionic, iso-butyric, isovaleric (containing α-methyl butyric) and n-valeric acids were produced under any environmental condition and acetic and iso-valeric acids usually showed a high value. The concentration of iso-butyric acid from Corynebacterium sp. was high in some cases. 2) In all the microorganisms acetic acid decreased and iso-valeric acid increased under the optimum condition for growth, and this trend was remarkable especially in the bacteria. In addition, the composition of FVFA from Vibrio sp. under the optimum condition for growth was similar to that in the stomach fluid of the porpoises (2). イルカ胃内から分離したグラム陽性細菌(Coryne-bacterium sp.),グラム陰性細菌(Vibrio sp.)およびC. tropicalis様酵母により,ペプトン・グルコース培地から生成する遊離の低級酸量と組成を,発育温度,pHおよび塩分濃度を変えてしらべ,次の結果を得た。1.各供試菌株について,いずれの環境条件下でも酢酸,プロピオン酸,iso酪酸,n酪酸,iso吉草酸(α-メチル酪酸を含む),n吉草酸を生成し,通常酢酸とiso吉草酸が多かった。なお,Corynebacterium sp.ではiso酪酸を多く含むこともあった。2.各供試菌株について,いずれも発育最適条件下では酢酸が減少し,iso吉草酸の増加を認めたが,とくに細菌はこの傾向が強かった。なお,Vibrio sp.の最適条件下での低級酸組成は胃内容液中の組成とよく類似した。 長崎大学水産学部研究報告, v.47, pp.43-48; 1979 departmental bulletin paper
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