Adhesion between cells of E. coli and pyrophyllite or kaolinite was studied quantitatively with the Coulter Counter. Cells adhered rapidly to a clay particle and formed a cell-clay complex. Cell-clay complexes were stable on the acid side and unstable on the alkaline side in the case of the clays homoionic to Na+ (BC complex of type I). Clays treated with Cu2+, Co2+ or Fe3+ adhered more cells than clays homoionic to Na+, and the complex was stable on the alkaline side and unstable on the acid side (BC complex of type II). Furthermore, the cell-clay complexes adhered to each other or to other clay particles and formed cell-clay aggregates at a much slower rate.
Catabolite repression of tryptophanase synthesis in E. coli K12 TAB40 was examined. The supply of glycerol or pyruvate to cells grown on each alternative carbon source reduced incorporation of either into the cells. Thus the synergistic effect on the catabolite repression of tryptophanase synthesis by combined supply of glycerol and pyruvate was presumed to be the result of metabolic alteration due to the alternative supply of the carbon source. Addition of arsenite to glycerol-grown cell repressed the tryptophanase formation. On the other hand, addition of arsenite to the pyruvate-grown cell derepressed the enzyme formation. This phenomenon was also seen in β-galactosidase system. Catabolite repression caused by glycerol plus pyruvate, therefore, was considered to be governed by the balance between glycolysis and gluconeogenesis. Intracellular pool of phosphoenolpyruvate (PEP) increased when catabolite repression was brought about, but little pool was seen when not repressed. ATP and FDP pool showed no appreciable change whether the repression was present or not. Conclusively PEP is assumed to play an important role in catabolite repression.
S-(2-Aminoethyl)-L-cysteine (AEC), a sulphur analog of L-lysine, inhibited the growth of Bacillus subtilis and Escherichia coli. In the case of Brevibacteriumflavum, AEC alone inhibited the growth rather weakly but in the presence of threonine the inhibitory effect was markedly enhanced. These inhibitory effects were diminished by the addition of L-lysine. AEC-Resistant mutants were derived from B. flavum No. 2247. Some of them produced much lysine in minimal medium and were not affected by threonine, differing from the lysine-producing auxotrophs or the threonine- or methionine-sensitive lysine producer. Therefore, the mutation site of lysine-producing AEC-resistants is deduced as the feedback site of aspartokinase.
An inorganic orthophosphate-activation of resting respiration in the intact cells of Brevibacterium ammoniagenes, tentatively named the "Pi-effect", was further investigated in comparison with oxidative phosphorylation. The "Pi-effect" was very susceptible to chemical modification of cell structure and completely arrested by lysozyme treatment. Five mM of MgCl2 protected the "Pi-effect" from lysozyme, though it could not repress an increase in cellular permeability of NADH caused by lysozyme. Efficiency of phosphorylation to respiration determined both in vivo and in vitro was almost unchanged by lysozyme treatment. The ratios of Pi/O, which was calculated by a method similar to that for ADP/O, and P/O in vivo and in vitro were about 0, 0.05, and 0.1 to NADH, respectively, and 1.0, 0.25, and 0.8 to succinate, respectively. Inhibitors and uncouplers such as p-quinone, menadione, arsenate, o- phenanthroline, pentachlorophenol, and tributyltin chloride, which markedly reduced the efficiency of oxidative phosphorylation, also acted to abolish the "Pi-effect" without exception.
The formation of 11α-hydroxyallopregnane and 6β, 11α-dihydroxyprogesterone, obtained when Rhizopus nigricans REF 129 was applied 11α-hydroxyprogesterone, was controlled by the addition of some redox agents and trace metals to the fermentation medium. The addition of Methylene Blue greatly reduced the concentration of 11α-hydroxyallopregnane. Moreover, potassium ferricyanide completely inhibited its formation. When the experimental organism was grown on Zn2+-deficient medium, the formation of 6β, 11α-dihydroxyprogesterone from 11α-hydroxyprogesterone was markedly restricted. However, the addition of Zn2+ (0.002-0.004μg Zn2+/ml) or Cd2+ (0.002mg/ml) stimulated the formation of 6β, 11α-dihydroxyprogesterone. On the other hand, the addition of Cd2+ (0.004mg Cd2+/ml) nearly inhibited the formation of 6β, 11α-dihydroxyprogesterone. Similar results were obtained when progesterone was charged to the medium supplemented with either potassium ferricyanide or Cd2+ (0.004mg Cd2+/ml). Under these conditions, a notable increase in the concentrations of 11α-hydroxyprogesterone and epicortisol was observed, but the transformation of the other transformation products, 17α-hydroxyprogesterone, 21-hydroxyprogesterone, and 11α, 17α-dihydroxyprogesterone, remained unaffected.
About half of the phleomycin-resistant progenies derived from Bacillussubtilis 160 were genetically unstable and yielded morphological, nutritional, and growth-rate mutants at considerably high frequencies. The high mutability was evidently transferred to another strain by the DNA-mediated transformation technique. The phleomycin gene and the mutability- controlling gene appeared to be located near the streptomycin and erythromycin loci.
Alcoholic methylene blue was shown to be a suitable stain for the Nadi- positive γ particles in zoospores of Blastocladiella emersonii; it was then used to establish the presence of similar particles in the uniflagellate spores of B. britannica and B. simplex. An average of 11-12 particles/spore was found in all three species, thus emphasizing the possibility that γ might be useful for taxonomic evaluations among the Blastocladiales. The gametes of B. cystogena also contain an average of 11.0 particles. In B. emersonii, however, the number of γ particles/spore was increased by growing RS plants in the presence of exogenous bicarbonate.
Addition of novobiocin and its benzoic acid moiety, 3-(3-methsl-2-butenyl)-4-hydroxybenzoic acid to growing cells of Staphylococcus aureus, most of which contain a penicillinase plasmid bearing determinants for penicillinase production, results in a decrease in penicillinase-producing cells and an increase in cells that do not make the enzyme. Two other benzoic acid derivatives, methyl 3-(3-chloro-2-butenyl)-4-hydroxybenzoate and ethyl 4-hydroxy-3-isopentylbenzoate cause a similar population shift. The induced change in ratio of penicillinase-producing to nonproducing cells is due to a selective action by the compounds in favor of cells which do not make penicillinase. There is no evidence that the compounds eliminate plasmids from the cells.
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)