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  • 1
    ISSN: 1432-072X
    Keywords: Coryneform Hydrogen Bacterium ; Autotrophic Growth ; Entner-Doudoroff Pathway ; Hydrogenase ; Slime Formation ; Corynebacterium autotrophicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Corynebacterium autotrophicum strain 7 C was isolated from an enrichment culture designed for propane oxidizing bacteria. The cells are Grampositive, immotile, short, irregularly formed rods. The colonies are yellow-pigmented and slimy. The yellow pigmentation is due to carotenoids. 2. Growth occurs either autotrophically in mineral medium under an atmosphere of 70% H2+20% O2+10% CO2 or heterotrophically with fructose or many organic acids as substrates. 3. The hexoses and gluconate are degraded via the Entner-Doudoroff pathway. 6-Phosphogluconate dehydrogenase is not detectable. 4. A NAD reducing hydrogenase has not been detected; the hydrogenase is localized in the particle fraction of the crude extract and reduces methylene blue. The specific activity of hydrogenase in the crude extract of autotrophically grown cells is 2400 μl H2/mg protein · hr. During growth on fructose the enzyme is constitutively formed (1200 μl H2/mg protein · hr). 5. The utilization of fructose was suppressed by hydrogen. The inhibitory effect was significant, when either fully adapted or autotrophically grown cells were exposed to a hydrogen containing atmosphere.
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  • 2
    ISSN: 1432-072X
    Keywords: R-Bodies ; Kappa particles ; Free-living hydrogen bacteria ; Induction ; Electron microscopy ; Chemical composition ; Defective prophages ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract R-Bodies have been found in a recently isolated pseudomonas-like free-living hydrogen oxidizing bacterium. Their isolation, fine structure and chemical composition are described and compared with the R-bodies from the kappa particles (Caedobacter), obligate endosymbionts of Paramecium aurelia. The 2K 1 R-bodies exhibited essential characteristics of the kappa R-bodies; however, their size and some other structural aspects proved that they represent a new type of R-bodies. The presence of phage tail-like particles in cells induced with Mitomycin C is in favour of the hypothesis that the R-bodies might be coded by defective prophages, or by extrachromosomal elements.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Selection of Slime-Free Mutant ; Coryneform Hydrogen Bacterium ; Capsular Material ; Bacterial Polysaccharide ; Chemostat Selection ; Selective Advantage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A slime-free mutant was isolated from Corynebacterium autotrophicum strain 7 C. The mutant appeared in a substrate (fructose) limited chemostat culture. No significant differences between wildtype and mutant were detected with respect to pigmentation, to growth rate, and respiratory rate at varying substrate (fructose) concentrations. During growth in chemostat culture the wildtype/mutant ratio present in the inoculum was maintained for weeks. The results do not explain the selection of the mutant in the substrate limited chemostat culture. The slime is a polysaccharide containing glucose, mannose and galactose; the uronic acid present was not identified. Copious amounts are produced from fructose, less from lactate or during autotrophic growth. The slime is not reutilized.
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  • 4
    ISSN: 1432-072X
    Keywords: Aquaspirillum autotrophicum ; Hydrogen bacterium ; Growth ; Chemolithoautotrophy ; Particulate hydrogenase ; Induction ; Repression ; Natural habitats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aquaspirillum autrotrophicum, an aerobic hydrogen bacterium recently isolated from an eutrophic freshwater lake, was characterized physiologically. It grew autotrophically in a fermenter with a doubling time of 4 h. Heterotrophic growth was faster. pH-Optimum ranged from 5.0–7.5, temperature optimum was about 28° C. During autotrophic growth about 10 moles hydrogen were consumed per 1 mole carbon dioxide fixed. Hydrogenase activity is inducible. CO2 did not enhance the oxy-hydrogen reaction by intact cells. The hydrogenase activity was localized in the particulate fraction. The hydrogenase reduced methylene blue and phenazine methosulfate; pyridine nucleotides were not reduced. In cell-free extracts, hydrogenase was sensitive to oxygen. Ribulosebisphosphate carboxylase was present in autotrophically-grown cells and absent from heterotrophically grown cells. Hydrogenase induction in heterotrophically-grown cells followed parabolic kinetics. Oxygen and D-gluconate repressed hydrogenase synthesis, whereas citrate, DL-lactate and pyruvate stimulated its formation. The repressive effect was delayed. The results suggest that the control of hydrogenase synthesis occurred at the transcriptional level, and that mRNA coding for the hydrogenase had a relatively long life span. D-Gluconate was degraded via the Entner-Doudoroff pathway, the enzymes of which were constitutively formed. Enzymes of the pentosephosphate and Embden-Meyerhof pathways (except phosphofructokinase) were present, too. Hydrogen did not inhibit heterotrophic growth. The possible competitive advantage of the physiological properties described with regard to the natural habitat was discussed.
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