Caulobacter daechungensis sp. nov., a stalked bacterium isolated from a eutrophic reservoir

A Gram-stain-negative, aerobic, non-spore-forming, curved, rod-shaped bacterium, H-E3-2(T), was isolated from a water sample taken from Daechung Reservoir, Republic of Korea, during the late-blooming period of cyanobacteria. Strain H-E3-2(T) was motile with a single polar flagellum or non-motile (stalked cell). Comparative 16S rRNA gene sequence studies showed the isolate had a clear affiliation with the class Alphaproteobacteria and was most closely related to Caulobacter fusiformis ATCC 15257(T) and Caulobacter mirabilis LMG 24261(T), showing 97.6 and 97.3 % 16S rRNA gene sequence similarity, respectively, and 95.3-96.3 % similarity to all other species of the genus Caulobacter. The predominant ubiquinone was Q-10. The major fatty acids were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) and C16 : 0. The G+C content of the genomic DNA of strain H-E3-2(T) was 64.7 mol%. DNA-DNA hybridization values of strain H-E3-2(T) with C. fusiformis ATCC 15257(T) and C. mirabilis LMG 24261(T) were 21.2 and 19.7 %, respectively. Thus, based on the results of polyphasic analysis, it is proposed that strain H-E3-2(T) represents a novel species of the genus Caulobacter, for which the name Caulobacter daechungensis sp. nov. is proposed. The type strain is H-E3-2(T) ( = KCTC 32211(T) = JCM 18689(T)).