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PubMedDate not supplied

[Carbon metabolism of filamentous anoxygenic phototrophic bacteria of the family Oscillochloridaceae].

The carbon metabolism of representatives of the family Oscillochloridaceae (Oscillochloris trichoides DG6 and the recent isolates Oscillochloris sp. R, KR, and BM) has been studied. Based on data from an inhibitory analysis of autotrophic CO2 assimilation and measurements of the activities of the enzymes involved in this process, it is concluded that, in all Oscillochloris strains, CO2 fixation occurs via the operation of the Calvin cycle. Phosphoenolpyruvate (PEP), which is formed in this cycle, can be involved in the metabolism via the following reaction sequence: PEP (+ CO2) --> oxalacetate --> malate --> fumarate --> succinate --> succinyl-CoA (+ CO2) --> 2-oxoglutarate (+ CO2) --> isocitrate. Acetate, utilized as and additional carbon source, can be carboxylated to pyruvate by pyruvate synthase and further involved in the metabolism via the above reaction sequence. Propionyl-CoA synthase and malonyl-CoA reductase, the key enzymes of the 3-hydroxypropionate cycle, have not been detected in Oscillochloris representatives.

Acetates↗
PubMed2005

Anaerobic transformation of tetrachloroethane, perchloroethylene, and their mixtures by mixed-cultures enriched from contaminated soils and sediments.

The focus of this research was to investigate the anaerobic transformation of tetrachloroethane (TeCA), perchloroethylene (PCE), and their mixtures by mixed cultures enriched from contaminated soils or sediments. Batch transformation studies were conducted using TeCA (60 microM), PCE (60 microM), or TeCA + PCE (each added at 60 microM) as electron acceptor(s) and H2 + acetate (each added at 3 mM) or butyrate (3mM) as electron donor(s). A Dehalococcoides spp.-containing, sediment-enrichment dechlorinated PCE rapidly to ethene (ETH) but slowly and incompletely dechlorinated TeCA. Moreover, when present in mixture with PCE, TeCA disrupted the ability of Dehalococcoides to dechlorinate vinyl chloride. In contrast, the soil-enrichment culture was able to completely dechlorinate TeCA and PCE to ETH, both when added as single contaminants and when added as a mixture.

Acetates↗
PubMedDate not supplied

[Factors controlling the biosynthesis of chlorosome antenna bacteriochlorophylls in green filamentous anoxygenic phototrophic bacteria of the family Oscillochloridaceae].

We determined the concentrations of bacteriochlorophylls (BChl) in the light-harvesting antennae of Oscillochloris trichoides (of the family Oscillochloridaceae belonging to green filamentous mesophilic bacteria) cultivated either with gabaculine, an inhibitor of the C-5 pathway of BChl biosynthesis in a number of bacteria, or at various illumination intensities. We determined the BChl c: BChl a molar ratios in intact cells, in chlorosome-membrane complexes, and in isolated chlorosomes. We revealed that BChl c synthesis in Osc. trichoides was more gabaculine-sensitive than BChl a synthesis. Accordingly, an increase in gabaculine concentrations in the medium resulted in a decrease in the BChl c: BChl a ratio in the tested samples. We suggest that BChl synthesis in Osc. trichoides proceeds via the C-5 pathway, similar to representatives of other families of green bacteria (Chlorobium limicola and Chloroflexus aurantiacus). We demonstrated that the BChl c: BChl a ratio in the chlorosomes varied from 55 : 1 to 110 : 1, depending on light intensity. This ratio is, therefore, closer to that of Chlorobiaceae, and it significantly exceeds the BChl c: BChl a ratio in Chloroflexaceae.

Bacterial Proteins↗
PubMedDate not supplied

[Phylogeny of anoxygenic filamentous phototrophic bacteria of the family Oscillochloridaceae as inferred from comparative analyses of the rrs, cbbL, and nifH genes].

Phylogeny of anoxygenic filamentous phototrophic bacteria (AFPB) of the family Oscillochloridaceae (Oscillochloris trichoides DG6T and the recently isolated strains Oscillochloris sp. R and C6) was studied based on comparative analyses of the genes coding for 16S rRNA (rrs), ribulose- 1,5-bisphosphate carboxylase/oxygenase (cbbL), and nitrogenase (nifH). The sequences of the genes studied proved to be identical in the three strains, which is in agreement with data obtained earlier that showed lack of differentiating phenotypic distinctions between these strains; therefore, it is proposed that the new strains should be identified as representatives of the species O. trichoides. Using an earlier designed system of oligonucleotide primers and a specially designed additional primer, fragments of the cbbL genes of the "red-like" form I RuBPC were amplified and sequenced for all of the O. trichoides strains. Analysis of the cbbL genes suggested a separate position of the bacteria studied in the phylogenetic tree, where O. trichoides strains formed an independent branch, which, apart from this species, also included the only studied species of gram-positive facultatively chemoautotrophic bacteria, Sulfobacillus acidophilus. In the phylogenetic tree inferred from the analysis of nifH genes, the bacteria under study also formed a new separate branch, deviating near the root, which indicated lack of relatedness between them and other phototrophic bacteria. The data obtained support the conclusion that AFPB has an ancient origin and their identification as one of the main evolutionary lineages of eubacteria, which was made based on the analysis of ribosomal genes.

Bacteria, Anaerobic↗