The adenine-sparing action of amino acid mixture (Difco "casamino acid" type) for inosine formation by adenine- and adenine-histidine-requiring mutants of Bacillus subtilis was revealed to be brought about by a combination of the following L-amino acids contained in the original mixture: histidine plus mixture of eight amino acids, isoleucine, leucine, methionine, glycine, valine, threonine, phenylalanine and lysine. Histidine was demonstrated to be essential, but the mixture of the eight amino acids could be fully replaced by a suitable concentration of phenylalanine alone. Histidine alone could not display the sparing action, and in the same way, the mixture of the eight amino acids or phenylalanine could not exert this action in the absence of histidine. A fairly large amount of certain amino acids mentioned above was required for expression of the sparing action by histidine. A minimal concentration of histidine for the sparing action with adenine-requiring mutant was about 7mg%, while a larger amount of it was required with adenine-histidine-requiring mutant. Inosine formation in 30mg% of adenine-added medium was strongly repressed by a large amount of amino acid mixture due to its adenine-sparing action, but the amount of 5-amino-4-imidazolecarboxamide riboside accumulated in this medium as a by-product, especially in the growing phase, was larger than that in the medium being suitable for inosine formation.
axonomic studies were carried out on yellow-pigmented bacteria which were found widely in paddy rice, fruit and other related plant materials, and they were included in Erwinia herbicola on the basis of flagellation and biochemical characteristics. Determination, nomenclature and relation to other allied bacteria of this species were discussed. Taxonomic position of the strains of Pseudomonas perlurida and Ps. trifolii, which were previously reported by the authors, was corrected.
Fermentation of glucose, nitrate reduction, nitrate respiration, nucleoside phosphotransferase, and pectolytic activity were tested on 132 strains of the genus Erwinia obtained from the culture collections. All the strains of Erw. Amylovora formed taxonomically homogeneous group, while the strains designated as Erw. Amylovora var. salicis were heterogeneous and belonged to various genera and species. The strains of Erw. Carotovora were taxonomically heterogeneous and some of them were members of the genera of Enterobacter and Serratia. The strains of Erw. herbicola were homogeneous as far as the characteristics tested were concerned. For a rapid differentiation of Erw. amylovora, Erw. arotovora, and Erw. herhicola, test of the characteristics mentioned above is considered to be useful.
The effect of manganese ion on promoting both the growth rate and cell yield of Agrobacterium tumefaciens in a synthetic medium containing sucrose as a sole source of carbon and energy was shown. In the experiments elucidating the effect of manganese ion, Mn2+, on cell yield from a point of growth energetics, following results were obtained. (1) On carbon balance during the culture, all carbons of sucrose consumed were recovered in the products, such as 3-ketosucrose, carbon dioxide and bacterial cells; (2) on the chemical composition, there was little difference in the cells grown in a medium with and without manganese ion, and it was also found that 90% or more of the dry cells was composed of protein, polysaccharide, lipid, RNA and DNA; and (3) the energy balance at logarithmic growth phase was calculated under the assumptions that energy is required for the synthesis of cellular macromolecules and for the active transport of sucrose from the medium, and that energy is derived from the oxidation of sucrose to 3-ketosucrose and carbon dioxide. In the absence of manganese ion in the medium, the efficiency of ATP for growth was calculated to be 22.6%, whereas by the addition of manganese ion at a concentration of 10-5M the efficiency was raised to 78.0%. From these results it can be inferred that manganese ion makes tight the coupling of ATP consumption with the growth of Agr. Tumefaciens.
Both complementary strands of coliphage mutant λdgA_J DNA, in which almost the entire left arm (genes A to J) is deleted (Fig. 2)., react with guanine-rich ribopolymers and show only marginal separation during centrifugation in the CsCl density gradient. The preparatively isolated "heavy" and "light" fractions of λdgA_J DNA were shown to correspond respectively to the "heavy" (C) strand and the "light" (W) strand of the wild-type λ or λcb2 DNA. This was ascertained by DNA-DNA hybridization between nonlabeled λdgA_J DNA fractions bound on nitrocellulose filters and 3H-thymidine-labeled, preparatively separated strands ofλcb2 DNA. This study shows that both strands of λdgA_J DNA have rather similar affinities for guanine-rich ribopolymers, but nevertheless the C strands of λdgA_J DNA contain somewhat more poly G-binding, dC-rich clusters than the W strands. It also provides a general method for identifying the separated strands derived from DNA fragments, obtained either by shearing or by isolation of DNA from appropriate deletion mutants of the phage.
Candida albicans grown in a liquid medium containing 0.5% D-xylose produced an adaptative NADP-polyol dehydrogenase which catalyzes the reversible reduction of some aldoses to the corresponding polyols. This enzyme was extracted from the culture and purified 134-fold using ammonium sulfate precipitations followed by calcium phosphate gel column chromatography. The Michaelis constant for D-xylose was determined to be 6.7×10- 3M. Heating of the enzyme up to 43° enhanced its activity, but it became completely inactive at 65°.
An NAD-polyol dehydrogenase present in cell-free extracts of Candida albicans, that catalyzes the reversible oxidation of xylitol to D-xylulose, was purified about 20-fold. The purified enzyme preparations catalyzed the oxidation of xylitol to D-xylulose, D-sorbitol to D-fructose and ribitol to D-ribulose. The relatively high activity with xylitol and D-xylulose suggest that they may benatural substrates for the enzyme.
Precipitated hydroxy-apatite and rock-phosphate dissolvers consisting of bacteria (Gram+and Gram-rods and cocci), fungi (Aspergillus, Penicillium, Rhizopus) and actinomycetes (Nocardia and Micromonospora) were isolated from 14 soils of Bihar in Eastern India on carrot-extract agar. Bacteria outnumbered fungi and actinomycetes. Fungi as a group had higher phosphate-dissolving capacity in a sucrose-peptone liquid medium than other organisms although some individual isolates of bacteria and actinomycetes could bring as much or more phosphate into solution. Many isolates which did not show clearance on carrot-extract agar could dissolve phosphate in the liquid medium suggesting that formation of solubilization zone is not sensitive to detect all phosphate-dissolving micro-organisms. Size of this zone was also not related with the phosphate-dissolving capacity of the organisms. Presence of calcium carbonate drastically reduced phosphate solubilization suggestive of a negligible role of micro-organisms in the availability of insoluble phosphates in calcareous soils. The solubilization of rock-phosphate was closely related to the growth of micro-organisms and aeration and pH conditions optimum for growth were also favourable to this process. Microbial solubilization of phosphate in these soils appeared to be a complex process involving diverse mechanisms such as formation of acids, alkalinity, hydrogen sulphide etc.
When the Japanese industrial strains of Aspergillus were cultured on rice, they produced various kinds of fluorescent substance, most of which were similar, in excitation and emission maxima and in thin-layer chromatograms, to those produced in the shaking culture reported in Part I. The aflatoxin productivity of 13 strains selected was further examined critically by culturing them on larger scales using two liters of the ADYE and MATELES' medium (stationary culture) and/or one kg of polished rice, and by measuring the UV absorption spectrum of the spots separated by thin-layer chromatography. The results showed that the fluorescent spots produced by these strains were classified into nine patterns, and that none showed the same absorption spectrum as that of aflatoxin. However, there still remains a question whether or not these fungi produce a trace amount of aflatoxin, which is rather difficult to prove by these cultivation methods. Since the presence of even a trace of aflatoxin in food should be avoided, it is desirable to find a correlation which may exist between the aflatoxin productivity of an organism and its mycological characters, by which the detection of aflatoxin-producing organism becomes easier and more accurate.