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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 147 (1987), S. 321-327 
    ISSN: 1432-072X
    Keywords: Propionate formation ; Ethanol fermentation ; Succinate pathway ; Petobacter propionicus ; Cytochrome b ; Anaerobic electron transport ; Pyruvate synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Whole cells of Pelobacter propionicus fermented (1-13C) ethanol and CO2 to nearly equal amounts of (2-13C) and (3-13C) propionate and to (1-13C) acetate indicating a randomizing pathway of propionate formation. Enzymes involved in the fermentation were assayed in cell-free extracts and cetyltrimethylammonium bromide-permeabilized cells grown with ethanol as sole substrate. Alcohol dehydrogenase, aldehyde dehydrogenase (benzylviologen-reducing), phosphate acetyl transferase, acetate kinase, pyruvate synthase, methylmalonyl CoA: pyruvate transcarboxylase, propionyl CoA: succinate CoA transferase, and the enzymes of the succinate-methylmalonyl CoA pathway all were detected at activities sufficient to be involved in ethanol fermentation. Very low amounts of a b-type cytochrome were detected in ethanol-grown cells (46 nmol δ g protein−1). Low cell yields obtained with ethanol as substrate indicate that P. propionicus does not conserve energy by electron transport-linked fumarate reduction. Despite the presence of a hydrogenase and a shift in the fermentation of lactate towards the formation of more propionate in the presence of hydrogen, P. propionicus was unable, to catalyze, the reduction of acetate and CO2 to propionate, unlike Desulfobulbus propionicus.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 152 (1989), S. 393-396 
    ISSN: 1432-072X
    Keywords: Betaine ; Desulfobacterium strains ; N,N-dimethylglycine ; Sulfate-reducing bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From enrichment cultures with betaine (20 mM) and sulfate (20 mM) as the substrates and intertidal mud as an inoculum, a betaine-oxidizing, sulfate-reducing bacterium (strain PM4) was isolated. Strain PM4 was an oval to rod-shaped, Gram-negative, motile bacterium, which was able to oxidize lactate completely to CO2 and contained, during growth on betaine and sulfate, high activities of key enzymes of the acetyl CoA/CO dehydrogenase pathway (carbon monoxide dehydrogenase and formate dehydrogenase), but not of 2-oxo-glutarate dehydrogenase, a key enzyme of the citric acid cycle. On the basis of its morphological and physiological characteristics, strain PM4 was identified as a Desulfobacterium strain. Desulfobacterium PM4 grew on betaine with a doubling time of approximately 20 h at 30°C and produced N, N-dimethylglycine (in a 1:1 ratio) and sulfide as products. In this type of betaine metabolism one of the methyl groups of betaine is oxidized to CO2 and the reducing equivalents generated are used for the reduction of sulfate. Desulfobacterium autotrophicum (DSM 3382) grew also on betaine and sulfate with the formation of N,N-dimethylglycine, sulfide and CO2.
    Type of Medium: Electronic Resource
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