A histidine auxotroph, AJ 3127 (ATCC 21349) derived from Brevibacteriumflavum ATCC 14067 which is a glutamic acid-producing bacterium, produces a large amount of L-histidinol from glucose and inorganic nitrogen. About 0.15g/liter of histidine or 40ml/liter of soybean protein hydrolyzate gives the maximum production of L-histidinol. The amount of L-histidinol accumulated in the presence of the latter is 9.2g/liter (as dihydrochloride). Among various substances supplemented to the medium, organic acids such as lactic acid, succinic acid, and malefic acid are found to enhance L- histidinol production. L-Alanine, L-phenylalanine, L-tryptophan, propionic acid, adenine, and 4-amino-5-imidazolecarboxamide riboside depress L-histidinol production. L-Histidine formation from L-histidinol is carried out by various bacteria including Brevibacterium flavum ATCC 14067.
When ground concentrated feed (10% w/v) was incubated in an artificial rumen with a ruminal microbial population from a hay-fed sheep, large amount of lactate accumulated after a short period (2 hr). On the contrary, with a population from a hay-concentrate fed animal, normal volatile fatty acid production was observed under the same conditions, and, although lactate accumulated at the early phase of incubation, it disappeared later. Removal of protozoa from these populations gave similar features with respect to the fermentation products. Accumulation of lactate at the later phase of incubation (4-6 hr), which was due to the activities of newly proliferated diplococcus- and streptococcus-type bacteria, occurred with both populations when the ratio of the concentrate to cell density became larger. The rate of glucose consumption of the hay-concentrate population at the initial phase was 5 times larger than that of the hay population. These results suggest that the increased capacity of sugar assimilation of the hay-concentrate population as compared to that of the hay population might prevent lactate accumulation at the later period by repressing the multiplication of lactate- forming bacteria by keeping concentration of easily fermentable carbohydrates at low levels.
Biotin-requiring baker's yeast died when aspartate was given to biotin- deficient cells harvested in later stage of exponential growth. The cells before addition of aspartate had no aspartic acid in the pool. After its addition, the cell components were rapidly synthesized and cells began to bud. However the budding cells lost the ability to multiply before nucleus was transferred to the bud cell, the amount of whose DNA increased approximately twice. Death did not occur at neutral pH or under an increased osmotic pressure of the surrounding fluid. This death was accelerated in the presence of chelating agents. The accelerating effect disappeared immediately on eliminating the chelating agents from the biotin-free medium. The site of action of chelating agents seems to be restricted only to the cell surface.
The DNA base composition (GC content) of 31 cultures of Debaryomyces and related yeasts including Torulaspora-type Saccharomyces was calculated from the thermal denaturation temperature (Tm) of DNA. The members of Debaryomyces and its imperfect forms exhibited GC contents from 32.4 to 45.6%, and were divided into 4 groups on the basis of this character. The first group had a GC content of 45.4-45.6%, and contained D. globosus, D. franciscae, and D. tamarii. The second group had the values of 42.4- 42.9% and consisted of D. nilssoni and 2 out of 6 strains of Torulopsiscandida. The third group showed the GC values of 36.6-37.3% and consisted of D. hansenii (including D. orientalis, D. nicotianae, D. kloeckeri, and D. subglobosus), D. marama, 4 out of 6 strains of T. candida, and Candida sp. The last group had a GC content of 32.4-34.4% and consisted of D. castellii, D. cantarellii, and D. vanriji. Torulaspora-type Saccharomyces (S. rosei-T. stellata, and S. fermentati-T. colliculosa) showed GC values (42.7-43.9%) similar to those of the second group. Strains of T. candida were separated into two groups, the second and the third. This suggests the heterogeneity of D. hansenii-T. candida. Of the members of the first group, D. tamarii does not seem to be closely related to the other two species of this group on the basis of antigenic structure in spite of a close resemblance in its GC content. Therefore, 4 or 5 groups are discriminated within this genus.
The studies were made on the reduced pyridine nucleotide-oxidizing enzymes in heterolactic bacterium, Leuconostoc mesenteroides IFO 3426, and it was confirmed that both NADH2 oxidase and NADPH2 oxidase were found in the supernatant fraction prepared by ultracentrifugation at 105, 000×g for 2hr. The purification and basal properties of these enzymes were described.
Serological and chemical properties of the two RNA phages, designated Y and Z, were investigated. Phage Y was serologically distinct from both phage β closely related to MS2 and phage I distinct from β. From this observation, the presence of at least three types of RNA phages was suggested. Phage Z was inactivated by antisera of I, Y, and β, and vice versa. s20, w values of Y and Z were estimated to be 82S and 77S, respectively. The species specificities of these phages were discussed from the aspects of chemical composition of the RNA and the serological relationship.
The phenomenon of exclusion in RNA phages of E. coli was investigated with four phages, β, I, Y, and Z, which could be distinguished from one another by their serological characters and plaque types. When E. coli cells were infected simultaneously with two serologically related phages, no exclusion was observed, but the exclusion was apparent when the cells were infected with two serologically unrelated phages. A phage having been judged to be highly "virulent" by the simultaneous infection method was excluded by a weakly "virulent" phage when tested by the superinfection method. The results obtained were compared with the exclusion phenomena in E, coli DNA phages.
DNA base composition (GC content) of 45 strains of Hansenula and related yeasts reported previously was re-examined by using an improved apparatus for determination of thermal denaturation temperature (Tm) of DNA. In addition to the strains mentioned above, GC contents of 17 strains representing 10 taxa were also investigated. The GC content of species of Hansenula ranged from 32 to 50%, and intrageneric variation was about 18%. The revised polygenetic scheme of Hansenula by Wickerham and the grouping of Hansenula based on proton magnetic resonance (PMR) spectra of mannans were evaluated from the viewpoint of the GC content. Several "natural" groups are deduced in the genus Hansenula on the basis of GC content, antigenic structure, PMR spectra of mannans, and criteria employed in the present system of yeast classification.
1. In biotin deficient yeast, thickening of cell wall was conspicuous at the middle log phase in the Am medium, whereas it was not in the aged cells. The cells cultivated in the Cas medium do not have thickened cell wall even in biotin deficiency. The ratio of mannan to glucan also decreased in the Cas medium, as well as in the Am medium, but, in pantothenic acid deficiency, the ratio did not decrease. In general, total amounts of glucan and mannan showed good parallelism with the thickness of cell wall observed in electron microscopy. 2. Investigations were made on the change of mannan and glucan of yeast at the process of the dead cell formation which appeared in the biotin- free aspartic acid medium and the results showed that mannan tended to increase.