Identification of sulfate-reducing bacteria strains of human large intestine

The sulfate-reducing bacteria have been isolated from human intestine. These bacteria are identified by their morphological, physiological and biochemical characteristics as the Desulfovibrio sp. and Desulfomicrobium sp. according to Bergey’s Manual of Determinative Bacteriology. Growth of the isolated strains of bacteria has been studied under various conditions including types of media, effect of oxygen, pH, and tempe­rature. Bacterial growth in the modified Kravtsov-Sorokin’s medium, and process of dissimilatory sulfate reduction by the selected strains of bacteria have been investiga­ted. All obtained bacterial cultures used sulfate and lactate intensively as well as produced hydrogen sulfide and acetate in the medium. The Desulfovibrio sp. strain Vib-7 produced the highest concentration (up to 3.23 mM) of hydrogen sulfide, while the bacteria used about 99% of sulfate ions presented in the medium. This strain also produced the highest concentration of acetate ions (up to 15.87 mM) on the fifth day of cultivation. Among the studied Desulfomicrobium sp. strains, the highest concentration of hydrogen sulfide was produced by the Desulfomicrobium sp. strain Rod-9, and the highest concentration of acetate ions was produced by the Desulfomicrobium sp. strain Rod-4. Keywords: sulfate-reducing bacteria, Desulfovibrio , Desulfomicrobium , identification, sulfates, hydrogen sulfide.