Twenty-two strains of hiochi-bacteria were analyzed for their deoxyribonucleic acid base composition and chemical composition of their cell wall. Guanine plus cytosine content of DNA (GC content) of hetero-fermentative true hiochi-bacilli ranged from 38.3 to 38.8%. As for homo-fermentative hiochi-bacteria, GC content of true hiochi-bacilli, which were grouped without regard to requirement of mevalonic acid, fell in the range of 34.6-36.8%. Chemical composition of the cell wall of these homo-fermentative true hiochi-bacilli was similar. These results were discussed with reference to the classification of hiochi-bacteria.
The water-soluble phenol-extracted fractions of the extracellular material from four strains of Rhizobium japonicum, differing in nodulating abilities, were analyzed by both chemical and physical methods to determine if there were any compositional similarities or differences in the carbohydrate, nucleic acid or protein fractions which might be related to the nodulation process. The composition of the water-soluble phenol-extract fraction of all four strains was essentially the same. In all four strains this fraction contained 3-9% carbohydrate, 5-15% ribonucleic acid, and less than 1% protein. The carbohydrate contained glucose, galactose, rhamnose, mannose, and glucosamine, plus two unidentified components. No uronic acids were present. The carbohydrate and nucleic acid moieties were partially separated on DEAE-Sephadex. Amino acid analyses indicated the protein to be of an acidic nature. On the basis of these data it would appear that the fractions of the extracellular material analyzed did not differ and could not be associated with a specific role in the nodulation process.
The biotin requirement of Lipomyces starkeyi IAM 4753 was tested in chemically defined media with variations in the initial pH. The strain exhibited normal growth in a glucose-mineral medium with a low initial pH (-5.5) and biphasic growth at a pH of 6.1. A supplement of biotin to the medium resulted in a rise of the pH to 6.5 at which normal growth occurred. Thus, it was considered that the yeast took up biotin from the medium with a high pH and supported their normal growth. When growing cells obtained from the glucose-mineral medium were analyzed for biotin, approximately 38 to 68 times as much biotin was detected as the amount of biotin which had been acquired from seed culture. Therefore, there was no obstruction in the biochemical sequence of the strain leading to the biosynthesis of biotin, but the strain has an enzyme system which is affected by culture pH.
The synthesis of alkaline phosphatase (APase) was found to be inducible in the wild type Escherichia coli P, and its γ-irradiation resistant mutants γ and 6γ, but constitutive in the 12γ strain. The specific activity of APase in γ, 6γ, and 12γ strains was two to five times greater than that of the P strain, even though the level of inorganic phosphate (Pi) to initiate the synthesis of this enzyme in the inducible strains was the same. Addition of different carbohydrates resulted in varying amounts of APase being synthesized by the inducible strains P, γ, and 6γ. This was not the case with the constitutive strain 12γ. In the absence of a carbohydrate, very little or no synthesis of APase was observed in the inducible strains but normal synthesis of this enzyme occurred in the constitutive strain. No differences were found in the catalytic properties of APase between the inducible and the constitutive strains of E. coli. These results suggest that carbohydrates, in addition to Pi, have an important role in the regulation of APase biosynthesis in inducible strains of E. coli.
Cell walls were prepared from both cultures of Candida albicans grown predominantly in the yeast-like (Y) and mycelial (M) phase, which developed in defined media containing biotin at a sufficient level (1ng/ml) and an insufficient level (0.1ng/ml), respectively, by mechanical disruption and washing. The comparative analysis of walls thus obtained showed that biotin-insufficient (M-phase) walls had greater quantities of alkali-insoluble glucan (or glucan-protein) but smaller quantities of mannan and alkali-insoluble glucan (or glucomannan-protein) than did biotin-sufficient (Y-phase) walls. Although there was no significant difference in the content of total proteins or lipids between the two forms of wall materials, the amino acid composition of polysaccharide-protein complexes and the fatty acid composition of lipids were distinctively characterized. Four layers were discernible by electron microscopy in the wall of C. albicans cells in both Y and M phases, but the outermost wall layer of biotin-insufficient cells appeared extremely thin as compared with that of biotin-sufficient cells. On the basis of these data, the role of such alterations in chemical composition and ultrastructure of walls or involved metabolisms, under the imposition of biotin insufficiency, in mycelial morphogenesis was discussed.
The rate of induced enzyme synthesis was formulated in general terms in line with a new account of the operon model by Yagil et al. who assumed originally two kinds of intracellular equilibria, one dealing with an effector (inducer) and free repressor, and the other, an operator and free repressor. The rate of induced aldolase synthesis in Azotobacter vinelandii was examined during the unsteady state realized by a stepwise change in rotation speed of an impeller in a chemostat culture of this specific bacterium. Some of the observations, exhibiting incidentally the first-order response time, were in compliance with an analytical solution of the above-mentioned formula, taking dissolved oxygen in the culture medium as an inducer. The first-order response in the rate of induced aldolase synthesis was given a new interpretation.
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Edited and published by : Applied Microbiology, Molecular and Cellular Biosciences Research Foundation/Center for Academic Publications Japan Produced and listed by : TERRAPUB, Center for Academic Publications Japan/Shobi Printing Co., Ltd. (-Vol.60,No12), Center for Academic Publications Japan/InternationalAcademic Printing Co., Ltd.(-Vol.54,No1)