Hypericibacter Terrae Gen. Nov., Sp. Nov. And Hypericibacter Adhaerens Sp. Nov., Two New Members Of The Family Rhodospirillaceae Isolated From The Rhizosphere Of Hypericum Perforatum

Two strains of the family Rhodospirillaceae were isolated from the rhizosphere of the medicinal plant Hypericum perforatum. Cells of both strains were Gram-stain-negative, motile by means of a single polar flagellum, non-spore-forming, non-capsulated, short rods that divided by binary fission. Colonies were small and white. Strains R5913(T) and R5959(T) were oxidase-positive, mesophilic, neutrophilic and grew optimally without NaCl. Both grew under aerobic and microaerophilic conditions and on a limited range of substrates with best results on yeast extract. Major fatty acids were C-19:0 cyclo omega 8c and C-16.0; in addition, C-16:1 omega 7c was also found as a predominant fatty acid in strain R5913(T). The major respiratory quinone was ubiquinone 10 (Q-10). The DNA G+C contents of strains R5913(T) and R5959(T) were 66.0 and 67.4 mol%, respectively. 16S rRNA gene sequence comparison revealed that the closest relatives (<92% similarity) of the strains are Oceanibaculum pacificum MCCC 1A02656(T), Dongia mobilis CGMCC 1.7660(T), Dongia soli D78(T) and Dongia rigui 04SU4-P-T. The two novel strains shared 98.6% sequence similarity and represent different species on the basis of low average nucleotide identity of their genomes (83.8%). Based on the combined phenotypic, genomic and phylogenetic investigations, the two strains represent two novel species of a new genus in the family Rhodospirillaceae, for which the name Hypericibacter gen. nov. is proposed, comprising the type species Hypericibacter terrae sp. nov. (type strain R5913(T)=DSM 109816(T)=CECT 9472(T)) and Hypericibacter adhaerens sp. nov. (type strain R5959(T)=DSM 109817(T)=CECT 9620(T)).