Strain G4-2T was isolated from the rhizosphere soil of alfalfa (*Medicago sativa* L.) in Dongying City, Eastern China. The isolate was rod-shaped, flagellate, motile and Gram-negative, and the colonies were flat, circular, beige and opaque. Strain G4-2T grew at salinities of 0-1% (w/v) NaCl (optimum, 0.5%), pH 6.0-9.0 (optimum, 8.0) and 20-50 °C (optimum, 37 °C). Phylogenetic and phylogenomic analyses based on the 16S rRNA gene sequence suggest that G4-2T belongs to the genus Microvirga and is most closely related to Microvirga vignae BR3299T. Its major fatty acid was C18 : 1 ω7c (68.3%). The polar lipid profile included phosphatidylethanolamine, phosphatidylglycerol and partially unidentified phosphoglycolipid. The sole respiratory quinone detected was ubiquinone 10. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain G4-2T and members of the Microvirga genus ranged from 74.0 to 90.3% and 20.3 to 42.0%, respectively. Both values are below the species delineation thresholds for species identification. Based on the result of the polyphasic characterization, we proposed a novel species in the genus Microvirga, Microvirga medicaginis sp. nov., the type strain of which was G4-2T (= ACCC 6437T = KCTC 18095T).
Zheng et al. (Tue,) studied this question.