A proposal for the reclassification of Bdellovibrio stolpii and Bdellovibrio starrii into a new genus, Bacteriovorax gen. nov. as Bacteriovorax stolpii comb. nov. and Bacteriovorax starrii comb. nov., respectively

ML Baer, J Ravel, J Chun, RT Hill and HN Williams Department of Oral and Craniofacial Biological Sciences, University of Maryland at Baltimore, 666 W. Baltimore Street, Baltimore, MD 21201, USA Bdellovibrios are unique bacteria with the ability to prey upon a wide variety of susceptible Gram-negative bacteria. Micro-organisms exhibiting this trait have been included in the genus Bdellovibrio despite their isolation from diverse habitats and relatively unstudied taxonomic relatedness. In this study, 16S rDNA sequences were compared from known terrestrial Bdellovibrio species, Bdellovibrio bacteriovorus 100(T), Bdellovibrio stolpii Uki2(T) and Bdellovibrio starrii A3.12(T) in order to study their phylogenetic relationship. The two sequences from B. stolpii Uki2(T) and B. starrii A3.12(T) were 90.0% similar to each other but exhibited only 81.7% and 81.2% similarity, respectively to B. bacteriovorus 100(T). Phylogenetic analysis indicated that B. bacteriovorus 100(T) clustered in a separate clade from B. starrii A3.12(T) and B. stolpii Uki2(T), demonstrating only a distant relationship between B. bacteriovorus 100(T) and the other two recognized type species. DNA--DNA hybridization experiments also demonstrated > 4% hybridization between these three species. On the basis of the results obtained from the phylogenetic analysis and DNA--DNA hybridization studies, it is proposed that B. stolpii Uki2(T) and B. starrii A3.12(T) should be transferred to a new genus, Bacteriovorax gen. nov. as Bacteriovorax stolpii comb. nov. and Bacteriovorax starrii comb. nov., respectively. It is also proposed that the type species for the new genus Bacteriovorax should be Bacteriovorax stolpii comb. nov.