Microvirgula curvata sp. nov., isolated from hydrocarbon-contaminated soil, and emended description of the genus Microvirgula

A novel Gram-stain-negative, small curved-rod-shaped, motile strain, designated L6T, was isolated from hydrocarbon-contaminated soils collected from Kuwait. Strain L6T was able to grow at 10-40 °C (optimum, 27-32 °C), pH 6.1-8.8 (optimum, 6.5-7.5) and 0-4.5 % (w/v) NaCl (optimum, 0-0.5). C18 : 1ω6c/C18 : 1ω7c, C16 : 0, C16 : 1ω6c/C16 : 1ω7c, C12 : 0 and C12 : 0 3-OH were predominant fatty acids with minor amounts of C14 : 0 and C17 : 0 cyclo. Phosphatidylglycerol and phosphatidylethanolamine were major polar lipids. The genomic G+C content was 61.2 mol%. 16S rRNA gene sequence comparisons indicated that strain L6T represents a member of the genus Microvirgula within the family Neisseriaceae of the class Betaproteobacteria. Strain L6T has a sequence similarity of 99.2 % with Microvirgula aerodenitrificans SGLY2T and <93.8 % with other members of the family Neisseriaceae. However, strain L6T showed only 56.5±2 % relatedness (based on DNA-DNA hybridization) with M. aerodenitrificans KACC 12055T (=SGLY2T). Distinct morphological, physiological and genotypic differences from the previously described taxa support the classification of strain L6T as a representative of a novel species in the genus Microvirgula, for which the name Microvirgula curvata sp. nov. is proposed. The type strain is L6T (=KEMB 2255-471T=JCM 31223T). An emended description of the genus Microvirgula is also proposed.