Proposals of Curvibacter gracilis gen. nov., sp nov and Herbaspirillum putei sp nov for bacterial strains isolated from well water and reclassification of [Pseudomonas] huttiensis, [Pseudomonas] lanceolata, [Aquaspirillum] delicatum and [Aquaspirillum] autotrophicum as Herbaspirillum huttiense comb. nov., Curvibacter lanceolatus comb. nov., Curvibacter delicatus comb. nov and Herbaspirillum autotrophicum comb. nov.

Two strains of curved bacteria, 7(.)1(T) and 7(.)2(T), isolated from well water, were phylogenetically examined to determine their taxonomic position. Strain 7(.)1(T) is a Gram-negative, slightly curved rod. Analysis of the 16S rRNA gene sequence showed that strain 7(.)1(T) formed a cluster with [Aquaspirillum] delicatum and [Pseudomonas] lanceolata. It has some similar characteristics to [A.] delicatum and [P.] lanceolata, but has sufficient distance to separate it from other genera. DNA-DNA hybridization analysis, as well as chemotaxonomic and morphological studies, demonstrated that strain 7(.)1(T), [A.] delicatum and [P.] lanceolata belong to a new genus, Curvibacter gen. nov. Strain 7(.)1(T) (=IAM 15033(T) =ATCC BAA-807(T)) is classified as the type strain of Curvibacter gracilis gen. nov., sp. nov., and [A.] delicatum and [P.] lanceolata are classified as Curvibacter delicatus comb. nov. and Curvibacter lanceolatus comb. nov., respectively. Strain 7-2(T) is a Gram-negative spirillum. Phylogenetic study based on the 16S rRNA gene sequences showed that it formed a cluster with the members of the genus Herbaspirillum, [Pseudomonas] huttiensis and [Aquaspirillum] autotrophicum. The classification is therefore proposed of strain 7-2(T) (=IAM 15032(T) =ATCC BAA-806(T)) as the type strain of Herbaspirillum joutei sp. nov., and [P.] huttiensis and [A.] autotrophicum are transferred to the genus Herbaspirillum as Herbaspirillum huttiense comb. nov. and Herbaspirillum autotrophicum comb. nov., respectively.