Amino Acid Metabolism of Sh. flexneri I. Relation between Growth and Amino-acid Metabolism

This experiment was conducted to examine the effect of aspartate and glutamate as N source and cysteine and methionine as S source for the growth of some strains belonging to Sh. flexneri, and the ability of amino acids syntheses by the resting cells of each strain. Thus the following results were obtained. 1. These organisms generally need aspartate or glutamate as N source and cysteine or methionine as S source, and many of them require nicotinamide. It is interesting that in each strain belonging to Sh. flexneri la, 3a, when growth medium is glutamate-cysteine system the organisms require nicotinamide, but when glutamate-methionine system, they do not require it. 2. If each of amino acids, such as aspartate, glutamate, alanine, is added to resting cells suspension independently, the formation of the other kinds of amino acids is little, but if each of them is added with glucose, the formation is great. At this time formed amino acids are mostly aspartate, glutamate and alanine, but to form valine from glutamate. and glucose with a strain in Sh. flex. 2b is peculiar. The above mentioned synthetic reaction of amino acids is remarkably accelerated by the addition of cysteine and methionine