Bacillus屬細菌の繁殖細胞並に胞子の榮養要求に就て

Abstract

(1) The nutritional requirements of vegetative cells, and spores of six aerobes, Bacillus natto, Bacillus subtilis, Bacillus, regatherium-I and -II, Bacillus mycoides, and Bacillus cereus, were studied by using a complete synthetic medium which has the composition as shown in Table 1. Four of the six strains could not grow in the complete medium containing 2.0 glucose. However, when the concentration of the basal medium was diluted to one-fourth of the original or when the concentration of glucose was reduced to 0.5%, both the vegetative cells and spores of all six strains showed good growth. Thereafter, we have used, as the basal medium, the one-fourth concentration of the original medium with 0.5% glucose. The spores of all strains except that of Bac. cereus did not grow without glucose in the medium. The ability to utilize ammonia has been tested by the medium in which the amino acids were replaced by ammonium acetate. The results were as shown in Table 2. (2) Purine and pyrimidine bases were not necessary for the growth of vegetative cells and spores of all strains. Vitamin requirement tests have showed that only biotin is necessary. for growth of Bac. natto and Bac. mycoides, and no vitamins are needed by the other four strains. It should be noted that there was no difference between vegetative cells and spores of each strain. (see Table 3). (3) Omission of each single amino acid ftom the mixture of eighteen amino acids in the basal medium showed that vegetative cells of all strains `and spores of the two strains (B. subtilis and B. mycoides) had no “indispensable” amino acid. However, the omisson of DL-isoleucine for the spores of B. natto, the omission of DL-valine for the spores of Bac. cereus, the omission of DL-valine, for the spores of Bac. cereus, the omission of DL-alanin or DL-threonine for the spores of B. megatherium (I), and omission of DL-phenylalanin for the spores of B. megatherium (II) completely inhibited the growth of each. (see Table 4). (4) Utilization of a single amino acid was studied using a medium which contains a certain amino acid as the sole N-source instead of the amino acid mixture. Among the nineteen amino acids tested, the five, L-glutamic acid, L-arginine, L-asparagine, L-hitidine, and L-proline, supported fair growth of the vegetative cells and spores of all, strains. No growth or only scanty growth of all strains was obtained by DL-threonine, L-cystine, DL-methionine, DL-tryptophan, or L-tyrosine. When glycine, DL-alanine, DL-valine, L-leucine, DL-isoleuciue, or DL-serine, was added as the sole N-source, it was frequently found that only the vegetative cells showed growth anti the spores of the same strain failed to o grow. (see Table 5) The differences in the amino acid requirements and in the, ability, to utilize a single amino acid between the vegetative cells and the spores of each strains eemed to be attributed only not to differences in the syntnetic ability but also to differences in the susceptibility to the toxicity of certain amino acids.