Mixotrophic metabolism in Burkholderia kururiensis subsp. thiooxydans subsp. nov., a facultative chemolithoautotrophic thiosulfate oxidizing bacterium isolated from rhizosphere soil and proposal for classification of the type strain of Burkholderia kururiensis as Burkholderia kururiensis subsp. kururiensis subsp. nov

A thiosulfate-oxidizing facultative chemolithoautotrophic Burkholderia sp. strain ATSB13T was previously isolated from rhizosphere soil of tobacco plant. Strain ATSB13T was aerobic, Gram-staining-negative, rod shaped and motile by means of sub-terminal flagellum. Strain ATSB13T exhibited mixotrophic growth in a medium containing thiosulfate plus acetate. A phylogenetic study based on 16S rRNA gene sequence analysis indicated that strain ATSB13T was most closely related to Burkholderia kururiensis KP23T (98.7%), Burkholderia tuberum STM678T (96.5%) and Burkholderia phymatum STM815T (96.4%). Chemotaxonomic data [G+C 64.0 mol%, major fatty acids, C₁₈:₁ ω7c (28.22%), C₁₆:₁ ω7c/15 iso 2OH (15.15%), and C₁₆:₀ (14.91%) and Q-8 as predominant respiratory ubiquinone] supported the affiliation of the strain ATSB13T within the genus Burkholderia. Though the strain ATSB13T shared high 16S rRNA gene sequence similarity with the type strain of B. kururiensis but considerably distant from the latter in terms of several phenotypic and chemotaxonomic characteristics. DNA-DNA hybridization between strain ATSB13T and B. kururiensis KP23T was 100%, and hence, it is inferred that strain ATSB13T is a member of B. kururiensis. On the basis of data obtained from this study, we propose that B. kururiensis be subdivided into B. kururiensis subsp. kururiensis subsp. nov. (type strain KP23T = JCM 10599T = DSM 13646T) and B. kururiensis subsp. thiooxydans subsp. nov. (type strain ATSB13T = KACC 12758T).