With 25 strains belonging to 12 species of the genus Bacillus, the base composition of DNA, the susceptibility to bacteriophages, and the ability to transform Bacillus subtilis strain MARBURG were studied. Analyses of phage DNAs were also performed. The results were as follows: (1) The DNA base compositions were not uniform even among strains belonging to one taxonomic species. (2) The DNAs extracted from B. natto, B. megaterium and B. polymyxa could transform genetic traits of B. subtilis MARBURG although the frequencies were not equal. (3) The host ranges of some temperate bacteriophages were correlated with the taxonomical data. On these bases, the phylogenetic relatedness of B. subtilis to B. megaterium was discussed.
The distribution of abilities of nitrate respiration and mode of cleavage of carbohydrates (oxidative or fermentative) were examined on the aerobic bacteria. The ability of nitrate respiration was only found in Gram-negative bacteria, such as Escherichia, Aerobacter, Erwinia, Serratia, Pseudomonas, Alcaligenes, etc., and was not found in the Gram-positive bacteria tested. The ability of fermentative cleavage of carbohydrates was widely distributed in aerobic bacteria, especially in Enterobacteriaceae. Meanwhile, Pseudomonas produced acid only oxidatively from glucose. As the members of Enterobacteriaceae were equipped with both the abilities of nitrate respiration and fermentative cleavage of carbohydrates, those of this family could be easily distinguished from the members of other families by testing both the abilities. The interrelation among the aerobic bacteria was discussed on the basis of the ability of nitrate respiration and the mode of cleavage of carbohydrates.
Bacillus cereus IAM 1299 has been found to produce large amounts of desthiobiotin in culture fluids (300-400mμg/ml nutrient broth); the production was, however, completely inhibited by the presence of excess biotin. Several lines of evidence are presented that the inhibition was due to repression and not to enzyme inhibition. The addition of actithiazic acid, an antagonist of biotin, enhanced the production of desthiobiotin. From the results presented here, the biosynthetic pathway from desthiobiotin to biotin is suggested to be narrow in this organism.
Using mutants lacking the ability to degrade 5′-nucleotides in B. subtilis M, enzyme repression in purine nucleotide biosynthesis was investigated. 1. The formation of IMP-transformylase was repressed by AMP or GMP derivatives and the formation of IMP-dehydrogenase repressed by GMP derivatives. 2. In a mutant devoid of GMP-reductase, growth was completely inhibited by a GMP derivative and this inhibition was completely overcome by the addition of a AMP derivative. 3. Among 125 guanosine-resistant mutants derived from a GMP-reductase negative mutant, several strains were found in which the formation of IMP-transformylase was resistant to the repressive effect of purine derivatives. In these strains, the formation of IMP-dehydrogenase was still sensitive to purines. The significance of the repression mechanisms in purine nucleotide biosynthesis was discussed.
Employing ultrathin sectioning and negative staining techniques, the reduction sites of tetrazolium salts (nitro blue tetrazolium=NBT, and triphenyl tetrazolium chloride=TTC) and of potassium tellurite in Clostridiumbotulinum and Cl. Tetani, were examined electron-microscopically. NBT and TTC were reduced to their formazans on or near the intracytoplasmic membrane system (ICMS) and the cytoplasmic membrane. It was presumed that in ultrathin sectioned preparations, owing to the dissolution of formazans in alcohol during the dehydration process, the sites of formazan deposition were seen as electron-transparent spaces among or around the unit membrane elements of the ICMS; moreover, a high tendency the cell wall to detach from the cytoplasmic membrane was noticed. Potassium tellurite appeared to be reduced mainly on or near the cytoplasmic membrane, but not on the ICMS. This result indicates that the sites of tellurite reduction do not necessarily coincide with those of reduction of tetrazolium salts.
Employing spores of Bacillus subtilis (Marburg strain), the role of L-alanine in the germination was examined. Spores of this organism can germinate in the presence of L-alanine or L-asparagine in a chemically defined medium but can outgrow only when L-glutamate is present in addition to either one of these amino acids. When the spores were grown in the alanine medium, in which only germination was induced, no net increase in nucleic acids was observed, whereas in the alanine-glutamate medium, in which germination and outgrowth occurred, a stepwise increase in RNA was demonstrated showing an appreciable lag during the germination period. When the spores were fed with L-alanine-14C, a slight but definite uptake of the tracer into spores was noticed during germination. This was confirmed by cell-fractionation experiments. A definite incorporation of L-alanine-14C into the RNA fraction during early germination was clearly demonstrated. The finding that the labeling of RNA with the tracer amino acid in the absence of net increase in RNA during germination is discussed as compared with similar observations in germinating Aspergillus conidia.
Using germinating spores of Bacillus subtilis Marburg, synthesis of macromolecules was studied by assay of radioactive amino acids and bases incorporated into protein and nucleic acid fractions. In spores heated at 70° for 10min, incorporation into protein and RNA fractions occurred simultaneously, but incorporation into DNA fraction about 40-50min later. But, when the spores were heated at 90° for 5min, "germination delay" was observed. In the spores, incorporation into RNA fraction occurred earlier than incorporation into protein. Early incorporation into protein was inhibited by actinomycin S, and later incorporation into RNA fraction was inhibited by chloramphenicol, puromycin and p-fluorophenylalanine. These agents also inhibited the incorporation into DNA fraction. On these grounds, the possibility was discussed that synthesis during germination occurred in a sequence of RNA, protein, and DNA, and the RNA synthesized in the early period of germination was essential for the following synthesis of protein, which might, in turn, play an important role in the subsequent synthesis of RNA and DNA during outgrowth.
Of the yeasts isolated from frozen foods, the following four new species of Candida were identified: Cand. curiosa, Cand. punicea, Cand. salmonicola and Cand. glaebosa. Cand. curiosa and Cand. punicea are included in the category of strict psychrophiles.