1) Utilization of various amino acids as the nitrogen source was tested with
Escherichia coli No. 1. It was thereby found that aspartic acid is utilized best, followed in that order by asparagine, glycine, arginine, serine, glutamic acid, alanine, and leucine, while phenylalanine, tryptophan, valine, proline, lysine, isoleucine, histidine, threonine, and methionine are not well utilized. Periodical change of such utilization was examined by varying the length of culture and it was found that the utilization of asparagine and serine was greatly increased by prolongation of culture time.
2) The utilization of compounds related to arginine as a nitrogen source was found to be in the decreasing order of urea, citrulline, arginine, and ornithine, the utilization of urea being especially marked. Since ornithine was detected in the medium provided with arginine as the nitrogen source, it was assumed that
E. coli No. 1 possesses an arginine-decomposing enzyme of arginine dihydrolase type.
3) The amino acid liberated into the medium during the growth of
E. coli No. 1 in inorganic medium was examined by a two-dimensional paper chromatography and aspartic acid, glutamic acid, alanine, valine, histidine, and methionine were detected. There seemed to be no direct relationship between the amount of these amino acid appearing in the medium and the rate of utilization.
4) Deamination of various amino acids by
E. coli No. 1 was examined and it was found that there is a parallel relationship between that and utilization of amino acids. The two were found to agree approximately in amino acids with low growth-promoting acitivity.
5) Oxygen uptake was measured with various amino acids as a substrate and it was found to be not stoichiometric with deamination reaction. It was therefore assumed that the deamination is other than oxidative.
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