Comparative characteristics of the Bdellovibrio strains isolated from river water and sewage

: The morphology, the host ranges, the resistance to pteridine and the nucleotide composition of DNA were compared in 12 newly isolated and 10 collection strains of Bdellovibrio. The significance of properties used for the taxonomy of these organisms was evaluated. The host ranges of Bdellovibrio strains are heterogeneous with respect to the taxonomy of host bacteria. The specificity of the parasite depends to a significant degree on the host bacterium in which it grows. All the strains including Bd. starrii which was described earlier as a pteridine resistant species are sensitive to pteridine. Therefore, such properties as the host range action and the response to pteridine cannot be used for diagnostics of Bdellovibrio species. The strains were found to be very heterogeneous with regard to the nucleotide composition of the DNA. Eight out of the 12 newly isolated strains were assigned to the species Bd, bacteriovorus.