Caulobacter ginsengisoli sp. nov., a novel stalked bacterium isolated from ginseng cultivating soil

Abstract

A Gram negative, aerobic, nonspore-forming, straight or curved rod-shaped bacterium, designated Gsoil 317T, was isolated from soil of a ginseng field in Pocheon Province (South Korea) and was characterized using a polyphasic approach. Cells were dimorphic, with stalk (or prostheca) and nonmotile or nonstalked and motile, by means of a single polar flagellum. Comparative analysis of 16S rRNA gene sequences revealed that strain Gsoil 317T was most closely related to Caulobacter mirabilis LMG 24261T (97.2%), Caulobacter fusiformis ATCC 15257T (97.1%), Caulobacter segnis LMG 17158T (97.0%), Caulobacter vibrioides DSM 9893T (96.8%), and Caulobacter henricii ATCC 15253T (96.7%). The sequence similarities to any other recognized species within Alphaproteobacteria were less than 96.0%. The detection of Q-10 as the major respiratory quinone and a fatty acid profile with summed feature 7 (C18:1 omega7c and/or C18:1 omega9t and/or C18:1 omega12t; 56.6%) and C16:0 (15.9%) as the major fatty acids supported the affiliation of strain Gsoil 317T to the genus Caulobacter. The G+C content of the genomic DNA was 65.5 mol%. DNA-DNA hybridization experiments showed that the DNA-DNA relatedness values between strain Gsoil 317T and its closest phylogenetic neighbors were below 11%. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain Gsoil 317T should be classified as representing a novel species in the genus Caulobacter, for which the name Caulobacter ginsengisoli sp. nov. is proposed. The type strain is Gsoil 317T (=KCTC 12788T= DSM 18695T).