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 317(T), 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 317(T) was most closely related to Caulobacter mirabilis LMG 24261(T) (97.2%), Caulobacter fusiformis ATCC 15257(T) (97.31%), Caulobacter segnis LMG 17158(T) (97.0%), Caulobacter vibrioides DSM 9893(T) (96.8%), and Caulobacter henricii ATCC 15253(T) (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 (C(18:1) omega 7c and/or C(18:1) omega 9t and/or C(18:1) (omega 12t; 56.6%) and C(16:0) (15.9%) as the major fatty acids supported the affiliation of strain Gsoil 317(T) 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 317(T) and its closest phylogenetic neighbors were below 11%. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain Gsoil 317(T) 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 317(T) (=KCTC 12788(T)= DSM 18695(T)).