During growth of the anaerobic acidogenic bacterium, Eubacteriumlimosum, on methanol-CO2, formate supplements were shown to influence both rates of growth and the ratio of organic acid fermentation end- products. Formate interrupted the oxidation of methanol to CO2 thereby lowering the yield of reducing equivalents. A consequence of this was a progressive shift towards acetic acid production at the expense of butyric acid, proportionate to the initial formate concentration. Such a finding supports the physiological model of this organism's methylotrophic metabolism, in which butyric acid production is related directly to the flux of methanol oxidation. At high formate concentrations, reversal of this catabolic pathway (i.e. assimilation of formate as methyl donor for acetyl- CoA formation) resulted in ATP-limited growth. E. limosum could not be acclimatized to growth on formate alone though the cells remained able to transform formate to CO2 after several transfers.
The apparent Km and Vmax values for urea uptake in Anabaena doliolum Bharadwaja were 250μM and 568nmol of urea (mg protein)-1hr-1. In comparison, Anacystis nidulans IU 625 showed lower affinity, Km being 400μM and Vmax 500nmol of urea (mg protein)-1hr-1. Urea uptake was optimal at pH 7.5, 15W m-2 illumination and 30°C. Maximum uptake was evident during the exponential growth phase. Cells pregrown on N2, urea or nitrate transported urea equally well, but there was essentially no uptake of urea in cells preincubated with ammonia for more than 24hr. Nevertheless, ammonia did not inhibit urea uptake by urea grown cells. But the uptake of ammonia was reduced in the presence of urea. N- deficiency invariably stimulated uptake of urea. Experiments under different metabolic conditions revealed that uptake is an active process driven mainly by cyclic photophosphorylation.
The interaction between clupeine sulfate (a protamine from herring milt) and the cytoplasmic membrane of Bacillus subtilis was investigated. Protoplasts of B. subtilis was lysed by clupeine and the lytic effect was directly proportional to the concentration of clupeine and time of exposure. The antibacterial action of clupeine was reversed by anionic phospholipids and the cell membrane of the bacterium. Clupeine was also found to bind and form a complex with the phospholipids. These results indicate that protamine bound primarily to the membrane phospholipids, which may result in damage to the membrane structure and function.
We studied the effect of clupeine sulfate on a vital membrane-bound enzyme (adenosinetriphosphatase or ATPase). Clupeine stimulated the Mg2+-ATPase activity to 250% of the control level but the stimulatory effect diminished with more than 200μg of clupeine/ml. Considering the vital metabolic functions of this enzyme it appears that the stimulatory effect of clupeine on this enzyme may contribute to the destruction of membrane function. Phosphatidylethanolamine, a typical membrane phospholipid inactivated and blocked the stimulatory effect of clupeine on the ATPase activity. In view of the strong interaction between clupeine and membrane lipids, the effect of clupeine on the membrane structure of Bacillus subtilis was studied by incorporating a hydrophobic fluorescent dye (1, 6-diphenyl- 1, 3, 5-hexatriene) molecule in the isolated cell membranes. Clupeine increased the fluorescence intensity and decreased the fluorescence polarization of the membrane dye environment. This indicated a structural change in the cell membrane.
A selective medium (KS5) for the isolation of Plesiomonas shigelloides and Aeromonas hydrophila from fresh water fish and water samples was developed by modifying the Rimler-Shotts medium (RS). KS5 medium contains fructose and sucrose as fermentable carbohydrates, and penicillin G and oleandomycin phosphate as selective inhibitors. The mean recovery rates for Plesiomonas and Aeromonas strains on KS5 plates were 93 and 67%, respectively. Plesiomonas strains formed whitish blue or blue colonies while Aeromonas strains produced yellow or yellow orange colonies. On differentiation between Plesiomonas and Aeromonas isolated from fresh water environments, their morphology on KS5 plates were fully consistent with the characteristics of each genus including O/129 sensitivity, starch hydrolysis, and lysine and ornithine decarboxylation. Anaerobic culture was recommended for the selection of Plesiomonas because some reference strains of Pseudomonas could grow on KS5 plates under aerobic conditions. At the drainage outlet of tilapia culture ponds and within about 2km downstream, Plesiomonas shigelloides was isolated on KS5 medium in relatively high densities.
A new species of the genus Promicromonospora is described, for which we propose the name Promicromonospora sukumoe. Actinomycete strain SK-2049 contains lysine in the cell wall. The substrate mycelia of this strain fragment into bacillary and coccoid cells. It differs from previously described species of the genus Promicromonospora: P. citrea and P. enterophila. The type strain of P. sukumoe is strain SK-2049.
The phenotypic and chemotaxonomic characteristics of methanol-utilizing Hyphomicrobium strains were examined and compared with other related budding bacteria. These Hyphomicrobium strains are facultatively methylotrophic, and utilize methanol, but not methane, by the serine pathway with formaldehyde incorporation. The strains were divided into two species, Hyphomicrobium vulgare and Hyphomicrobium methylovorum, based on DNA base composition, and the activities of catalase and urease. The major cellular fatty acid is straight-chain unsaturated C18:1 acid. The major ubiquinone is Q-9. Strains in other similar budding bacteria in the genera Hyphomonas, Pedomicrobium, Rhodomicrobium, and Hyphomicrobiumindicum do not utilize methanol, have different DNA base compositions, possess different cellular fatty acids, and have different quinone systems. Based on the above data, the methanol-utilizing Hyphomicrobium strains are clearly distinguished from the supposedly related genera.
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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)