Part I Effet of N and C-sources on Growth, of Vibrio Cholera Using the 3 strains of Vibrio cholera as test organisms, the original strain (INABA's strain), the intermediate variant strain (HIKOZIMA's strain) and the variant strain (OGAWA's strain), the author studied the effect of N- and C-sources on growth of these microorganisms, and obtained the following results. 1) The intermediate variant strain could be cultured by serial transfers on the madia containing glutamate as N-source and did not need other C-source or vitamins for its growth. While the other 2 strains, the original and the variant strains, could not be cultred successfully without the addition of yest extract into the media. Also these 2 strains could be cultured by serial transfers on the media containing peptone or casein hydrolysate instead of yeast extract, but failed to grow on the madia containing some dozen species of amino acids. 2) An acceleration effect on growth of the microorganisms was not so remarkable as in the case of other bacteria by the addition of C-sources except lactate. Although the addition of lactate showed the acceleration effect fairly well, contrarily that of glucose acted rather inhibitory on the growth. This evidence was possibly arisen from a decrease of pH of the media being caused by the oxidation of glucose. Part 2 Amino Acids Metabolism of Resting Cells Using the 3 strains of Vibrio chlera as in the preceding paper, Part I, the author studied on the oxidation and the convertion of amino acids by these microorganisms and obtained the following results. 1) All the microorganisms tested showed an accelerated O2-uptake at the expense of aspartic acid, glutamic acid, alanine and cysteine as substrate; but showed rather small O(2)-uptake at the other amino acids. 2) The optimum pH was found to be at about 7.0 on the oxidation of aspartic acid, glutamic acid and alanine. And the amino acids mentioned here were oxidized through deamination at the pH ranging 5.0 to 8.0. 3) The convertion of the amino acids from these mentioned above to the others was carried out more successfully by these microorganisms compared with the other. 4) Concerns about the fate of oysteine, it was supposed this amino acid would be undergone in the first place a deamination and a desulfhydration resulting in pyruvate. 5) Though tryptophanase activity was observed to some extent on the bacterial cells harvested from media just before test, the activity was raised adaptatively by the shaking of the resting cell suspension in the presence of tryptophane. However, this adaptation of microorganisms was inhibited with the addition of glucose.