Rhodococcus sovatensis sp. nov., an actinomycete isolated from the hypersaline and heliothermal Lake Ursu

A Gram-stain-positive, strictly aerobic, mesophilic bacterium, designated H004T, was isolated from a water sample of the hypersaline and heliothermal Lake Ursu, Sovata, Romania. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain H004T formed a distinct phyletic lineage within the genus Rhodococcus. It shared the highest 16S rRNA gene sequence similarity with Rhodococcus yunnanensis YIM 70056T (98.80 %), followed by Rhodococcus fascians LMG 3623T (98.73 %), Rhodococcus cercidiphylli YIM 65003T (98.73 %), Rhodococcus cerastii C5T (98.58 %) and Rhodococcus kyotonensis DS472T (98.53 %). The alkB-based phylogenetic analysis further confirmed that this strain constitutes a highly unique lineage within the genus. Chemotaxonomic characteristics, including the predominant fatty acids acids C15 : 0, C18 : 1ω9c, C19 : 1ω11c/C19 : 1ω9c and C16 : 1ω7c/iso-C15 : 0 2-OH, the major quinone MK-8(H2), the presence of mycolic acids and cell-wall chemotype IV were also consistent with the properties of members of the genus Rhodococcus. The DNA G+C content of strain H004T was 65.4 mol%. The results of DNA-DNA hybridization analyses with the closest relatives, in combination with the alkB-based phylogenetic analysis, as well as the chemotaxonomic and physiological data, demonstrated that isolate H004T represents a novel species of the genus Rhodococcus, for which the name Rhodococcus sovatensissp. nov. is proposed. The type strain is H004T (=DSM 102881T=NCAIM B.02632T).