In an attempt to clarify the taxonomic situation of the strain ATCC-15517, which is a well-known aflatoxin producing fungus, its general morphological and physiological characters, in addition to mutation by ultraviolet rays, were examined by comparing with many kinds of industrial strains used in Japan. From the results obtained, it seems that this fungus belongs to A. parasiticus rather than to A. flavus because of its remarkably rough walled conidia and conidiophores, sensitivity to heating, high productivity of acid, strong resistance to ultraviolet light, and other physiological observations, excluding its unstable arrangement of sterigmata. Thus, it should be placed in a new strain of A. parasiticus series by its globose-shaped vesicles: A. parasiticus Speare var. globosus MURAKAMI nov. var. Finally, it was confirmed that neither this fungus nor its allied strain was found at all in Japanese industrial strains, from the point of morphology.
The isolation and characteristics of actinophage (PK-66, PK-69, and PK-46) for Streptomyces kanamyceticus were described. Phage PK-66 were characterized with respect to the medium components essential for propagation, influence of pH, and medium components on stability, thermal inactivation rates, enzyme treatments, host range, and electron micrograph. The adsorption of phage PK-66 to Streptomyces griseus was found to decrease as the age of the recipient mycelium increased.
(1) An isoleucine auxotrophic mutant named No. 14-5 (ATCC No. 15940), derived from Brevibacterium flavum 2247 (ATCC No. 14067), produces a large amount of L-proline directly from sugar and inorganic nitrogen. (2) The optimum concentration of L-isoleucine for the maximum production of L-proline is about 15mg/dl. (3) Glucose and starch hydrolyzate are the most suitable carbon source for L-proline production, and 3-7%, especially 5.5%, of ammonium sulfate is the most favorable as inorganic nitrogen source. About 450μg/liter of biotin is necessary for abundant production of L-proline. Under these conditions, more than 1.2g/dl of L-proline is able to be produced in the medium from 10% glucose after shaking culture at 31° for 72hr. (4) It is observed that the combination of three major chemical components, i.e., L-isoleucine, biotin, and ammonium sulfate, is very important for abundant production of L-proline. As the role of these components, the following conclusion was obtained. (i) Some interrelation exists between isoleucine and proline biosynthesis. (ii) High concentration of biotin serves to restrain extracellular glutamic acid production and, to increase proline production, as well as to promote the growth of this microorganism. (iii) High NH+4 concentration, equivalent to 5.5% of ammonium sulfate against 10% glucose, is effective for increasing the accumulation of proline itself, as well as for decreasing by-product formation of alanine and valine.
1) Yeast cells suspended in a solution of cetyltrimethylammonium bromide (CTAB), a typical cationic detergent, rapidly bind CTAB cations. The binding process is nearly completed in less than 2min, while the germicidal action continues for at least 1hr. 2) The shape of overall binding curve shown by yeast cells is similar to that of multilayer adsorption isotherm. 3) The mortality of CTAB-treated cells depends upon the weight ratio of bound CTAB to yeast cells. Calculations show that 10 times the cell surface area must be covered by the bound CTAB to produce 100% killing of the samples.
Electron microscopic studies have been made on ultrathin sections of Aspergillus oryzae conidia fixed in potassium permanganate. Staining of sections in uranyl acetate solution was necessary to disclose the fine structure of dormant cells. Although the remarkable difference could not be seen between dormant and germinated conidia, some minor differences in membranous systems were noticed. In dormant conidium, invaginations of cytoplasmic membrane and the presence of unidentified membranous organelles were characteristic.
1) The respiratory activity of aerobically and anaerobically grown cells of Escherichia coli did not show marked difference when the substrate was glucose. The activity of anaerobically grown cells was distinctly lower than that of aerobically grown cells when respiration was measured on formate, acetate, malate, or succinate. 2) When anaerobically grown cells were aerated for 2.5hr in the absence of cell multiplication, the original low respiratory activity increased to a level of aerobically grown cells. 3) The development of respiratory activity in resting cells occurred only when several amino acids were present in the incubation mixture. The development was inhibited by ethionine, p-fluorophenylalanine, chloramphenicol, and glucose. The development was also inhibited by respiratory poisons such as cyanide, azide, carbon monoxide, and nitrophenols at concentrations that inhibited respiration of aerobically grown cells. 4) In aerobically grown cells a considerable amount of cytochromes a2 and b1, and a slight amount of cytochrome a1 were present, while in anaerobically grown cells these cytochromes were present in a remarkably diminished amount. The cytochrome content of anaerobically grown cells did not increase significantly when resting cells were aerated for 2.5hr in a buffer containing only amino acids, but did increase when aerated for 4hr in a mixture containing amino acids and beef extract.
The preferential synthesis of acid protease by Aspergillus niger mycelium in sulfur-deficiency was studied with special reference to the synthesis of cellular protein. During sulfur-deficiency, the synthesis of protease occurred preferentially but that of cellular protein (including acid phosphatase) did not, whereas in nitrogen-deficiency neither the former nor the latter occurred. Estimations of the amount of the amino acid pool and soluble protein fractions in mycelia and chasing of the radioactivities of these fractions of mycelia previously labeled with tracers showed that the amino acid pool together with the sulfur pool inherited from the previous culture seemed to be utilized, if at all, for the synthesis of cellular protein either in the presence or absence of sulfur source. When the specific radioactivities of protease produced from mycelia previously labeled with 14C-amino acids were estimated, it was strongly suggested that in sulfur-deficiency exogenous amino acids were incorporated into protease protein via pool amino acid.
Extraction and purification of soluble RNA (sRNA) from dormant and germinated conidia of Aspergillus oryzae were carried out. The direct extraction with water-saturated phenol of sRNA from intact cells, successfully employed in various organisms, was found employable only on germinated conidia but not on dormant ones. Therefore, in the present investigation sRNA from dormant and germinated conidia were extracted with sodium dodecylsulfate-phenol from the supernatant fraction of disrupted cells. The purification method finally adopted was the deoxyribonuclease digestion followed by the DEAF-cellulose column chromatography. Both the sRNA samples thus obtained from dormant and germinated conidia gave the sedimentation coefficient of 4S with a single and symmetric pattern. The nucleotide analysis of either sample also showed the composition characteristic to sRNA. The thermal denaturation profile was rather broad in comparison with yeast sRNA and Tm-value of 65° was obtained in 5mM MgCl2 (pH 7.6). Since the amino acid-acceptor activities of both samples were low, no final conclusion could be deduced wheather or not there were any difference in these activities between the two sRNA samples.