Використання фумарату бактеріями Desulfuromonas sp.
Utilization of fumarate by sulfur-reducing bacteria Desulfuromonas sp.

Summary/Abstract: The main goal of the work was to study the utilization of fumarate by sulfur-reducing bacteria Desulfuromonas sp. under different growth conditions and accumulation of hydrogen sulfide by bacteria in the media with sulfur and different electron donors. Sulfur-reducing bacteria Desulfuromonas sp., isolated from soil in Yazivske sulfur deposit, were used in the research. Bacteria were grown in the medium Postgate C without sulfates. The content of hydrogen sulfide was determined by formation of methylene blue. The content of organic acids (fumarate, succinate, lactate, acetate) was determined by high performance liquid chromatography (HPLC). The biomass of cells was determined by the photoelectrocolorymetry method using KFK-3. The highest level of accumulation of hydrogen sulfide by bacteria Desulfuromonas sp. was found in media with sodium lactate and sodium pyruvate. The maximal concentration of hydrogen sulfide was 1.9 mM. Maximal accumulation of biomass was observed in the media with malate, lactate and fumarate with the presence of elemental sulfur. Sulfur-reducing bacteria Desulfuromonas sp. are able to utilize fumarate as an electron donor and acceptor in the absence of elemental sulfur in the medium. After the incubation of Desulfuromonas sp. in the medium with fumarate, chromatographic analysis of culture liquid showed that fumarate is converted to succinate and small quantities of acetate The presence of acetate is, probably, due to the particularaties of the functioning of citric acid cycle in bacteria of the genus Desulfuromonas. Consequently, the results indicate that the fumarate serves as a donor and acceptor of electrons.The simultaneous introduction of two electron donors – fumarate and elemental sulfur – was accompanied by inhibition of sulfur reduction. After an additional source of carbon (sodium lactate) and electron acceptor (elemental sulfur) was added to the medium with fumarate a five fold increase of sulfidogenic activity was observed. Thus, regulation of respiration in bacteria Desulfuromonas sp. is directed to the primary utilization of the most energetically favorable electron acceptors.

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