- Volume 125, Issue 2, 1981
Volume 125, Issue 2, 1981
- Physiology And Growth
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Changes in Metabolic Activity of Proteus mirabilis during Swarming
More LessProteus mirabilis in the long, swarming form had altered metabolic activity compared with bacteria in non-swarming phases on solid media. During swarming the rates of incorporation of precursors into DNA, RNA and protein, as measured in broth cultures immediately after harvesting from swarm plates, were lowered. The rates of uptake of these precursors into the bacteria were also lowered, and at the same time the rate of oxygen uptake was reduced to less than 20 % of the normal rate, although intracellular ATP concentrations remained constant. The return of macromolecular synthesis and oxygen uptake to preswarming rates corresponded to the end of the active swarm period. The results indicate that in the multiflagellate swarmers of P. mirabilis metabolic activity was lowered to a level necessary to maintain flagella activity but not bacterial growth.
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Reversible Change of Mating Type in Phytophthora parasitica
More LessIn addition to the original mating type, the opposite mating type appeared in the zoospore population of single isolates of Phytophthora parasitica after long-term storage or chloroneb treatment. Occasionally self-fertile zoospores were also detected, but their self-induction nature was transitory and unstable. Both hormone production and hormone reception were changed in the sexual variants. The results explain the apparent change from cross-induction (‘heterothallic’) to self-induction (‘homothallic’) in P. parasitica after long-term storage and chloroneb treatment, and suggest one possible evolutionary origin of sex in the lower fungi.
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- Short Communications
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Mutants of Bacillus subtilis Affected in the Morphogenesis of Outgrowing Spores
More LessMutants of Bacillus subtilis temperature sensitive in spore outgrowth and showing altered morphology were examined by ultrathin sectioning and electron microscopy. Cells from spores outgrowing at 47 °C were often spherical with incomplete cross-walls. Cells intersected irregularly by randomly distributed cross-walls were also seen. The presence of sublethal doses of the antibiotic Distamycin A restored the ability to grow as rods, but did not completely restore the capacity to synthesize cross-walls in the correct position.
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Oscillatory Accumulation of Catalase during the Cell Cycle of Acanthamoeba castellanii
More LessThe accumulation of catalase in synchronously dividing cultures of Acanthamoeba castellanii, prepared by size selection techniques involving minimal perturbation, was discontinuous. During the cell cycle of 8 h both catalase activity and immunologically determined catalase protein oscillated with a periodicity of about 1 h and a mean trough-to-peak amplitude of 21% of the minimal values. These patterns of enzyme accumulation were not observed in control asynchronous cultures after exposure to identical experimental conditions. The results are discussed suggesting that periodic biosynthesis and degradation occurs during growth and division of this organism.
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Quantitative Analysis of Macrocyst Formation in Dictyostelium discoideum
More LessQuantitative studies are reported on macrocyst formation, the sexual cycle in Dictyostelium discoideum, under conditions in which asexual fruiting body formation is prevented. Light inhibited amoebae of both mating types from participating in macrocyst formation, and amoebae of the mata mating type responded better to a mating stimulus than amoebae of the matA mating type. These results are interpreted in terms of a possible two-way induction system leading to macrocyst formation in D. discoideum.
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- Taxonomy
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Quantitative and Qualitative Studies of Aeromonas salmonicida Bacteriophage
More LessA comprehensive bacteriophage typing scheme for Aeromonas salmonicida, the causal agent of furunculosis in fish, is described. It distinguishes 27 bacterial groups based on sensitivity patterns to 18 bacteriophage isolates. In addition, the sensitivity patterns are shown to reflect the morphological characteristics of the host bacterium. The ‘rough’,‘smooth’ and ‘G-phase’ forms possess different quantities of lipopolysaccharide in the cell wall and this influences bacteriophage attachment. The problems related to these morphological variations are discussed.
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Reproducible Pyrolysis‒Gas Chromatography of Micro-organisms with Solid Stationary Phases and Isothermal Oven Temperatures
More LessEight solid stationary phases were examined for their suitability for pyrolysis-gas chromatography (Py-GC) of micro-organisms. With temperature programming these phases offered little advantage over the traditional liquid phase Carbowax 20M, but at an isothermal analysis temperature of 100 °C their use solved many technical problems. Pyrograms were produced containing small numbers of baseline-resolved peaks which eluted within 8 to 25 min. Four to six specimens per hour could be examined with two pyrolysers attached to one chromatograph oven. When a control organism was used to derive normalized results, pyrograms were reproducible with a second column and a second pyrolyser, suggesting that inter-laboratory reproducibility may be possible.
Five different bacterial genera were well discriminated and some differentiation was achieved between different isolates of Streptococcus mutans, but similarity between pyrograms was unrelated to orthodox taxonomic grouping. The best discrimination was achieved with Chromosorb 104, followed by Chromosorb 101 and Tenax-GC. With solid phases and isothermal oven temperatures Py-GC is a promising technique for microbial identification.
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A Phylogenetic Analysis of Staphylococci, Peptococcus saccharolyticus and Micrococcus mucilaginosus
More LessThe intra- and intergeneric relationships of the genus Staphylococcus, and the phylogenetic position of Peptococcus saccharolyticus and Micrococcus mucilaginosus (Staphylococcus salivarius), were investigated by comparative oligonucleotide cataloguing of 16S rRNA. All the staphylococci investigated form a phylogenetically coherent group at the genus level that, in addition, contains the anaerobic species Peptococcus saccharolyticus. The genus Staphylococcus belongs to the broad Bacillus-Lactobacillus-Streptococcus cluster that is defined by Gram-positive bacteria with a low DNA G+C content.
Micrococcus mucilaginosus is not a genuine member of the genus Micrococcus. The binary matching coefficients between the 16S rRNA of Micrococcus mucilaginosus and those of representatives of the Arthrobacter/Micrococcus group and related genera indicate that Micrococcus mucilaginosus should be regarded as a member of a new genus.
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