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Abstract
The Gram-reaction-negative, aerobic, white- to pale-yellow-coloured and rod-shaped bacterium with a single polar flagellum or a stalk, designated strain 7F14T, was isolated from rhizosphere soil of cultivated watermelon (Citrullus lanatus) collected from Hefei, China. Growth of strain 7F14T was observed at pH 6.0–9.0, 10–30 °C and in the presence of 0–1 % (w/v) NaCl. Cells were catalase-negative and oxidase-positive. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain 7F14T formed a phyletic lineage within the genus Caulobacter of the family Caulobacteraceae and showed the highest 16S rRNA gene sequence similarities to Caulobacter henricii ATCC 15253T (98.66 %), Caulobacter segnis ATCC 21756T (98.27 %), Caulobacter vibrioides CB51T (97.92 %) and C aulobacter flavus RHGG3T (97.44 %). The G+C content of the genomic DNA was 68.6 mol%. Strain 7F14T contained Q-10 as the sole ubiquinone and 11-methyl C18 : 1ω7c, C18 : 1ω7c, C16 : 0 and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH) as the major fatty acids. The polar lipids profile consisted of phosphatidylglycerol, an unknown phosphoglycolipid, five unknown glycolipids, an unknown phospholipid and three unknown lipids. DNA–DNA relatedness values to the most closely related type strains Caulobacter henricii DSM 4730T and Caulobacter segnis DSM 7131T were 26.0 and 19.7 %, respectively. Based on unique phenotypic traits, and phylogenetic, chemotaxonomic and DNA–DNA hybridization results, strain 7F14T should be classified as a representative of a novel species of the genus Caulobacter , for which the name C aulobacter rhizosphaerae sp. nov. is proposed. The type strain is 7F14T (=CGMCC 1.15915T=KCTC 52515T).
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