Microvirga ossetica sp. nov., a species of rhizobia isolated from root nodules of the legume species Vicia alpestris Steven

Abstract

Gram-stain-negative strains V5/3M(T), V5/5K, V5/5M and V5/13 were isolated from root nodules of Vicia alpestris plants growing in the North Ossetia region (Caucasus). Sequencing of the partial 16S rRNA gene (rrs) and four housekeeping genes (dnaK, gyrB, recA and rpoB) showed that the isolates from V. alpestris were most closely related to the species Microvirga zambiensis (order Rhizobiales, family Methylobacteriaceae) which was described for the single isolate from root nodule of Listia angolensis growing in Zambia. Sequence similarities between the Microvirga-related isolates and M. zambiensis WSM3693(T) ranged from 98.5 to 98.7% for rrs and from 79.7 to 95.8% for housekeeping genes. Cellular fatty acids of the isolates V5/3M(T), V5/5K, V5/5M and V5/13 included important amounts of C-18 : 1 omega 7c (54.0-67.2 %), C-16 : 0 (6.0-7.8 %), C-19 : 0 cyclo omega 8c (3.1-10.2 %), summed feature 2 (comprising one or more of iso-C-16 : 1 I, C-14 : 0 3-OH and unknown ECL 10.938, 5.8-22.5 %) and summed feature 3 (comprising C-16 : 1 omega 7c and/or iso-C(15 : 0)2-OH, 2.9-4.0 %). DNA-DNA hybridization between the isolate V5/3M(T) and M. zambiensis WSM3693(T) revealed DNA-DNA relatedness of 35.3 %. Analysis of morphological and physiological features of the novel isolates demonstrated their unique phenotypic profile in comparison with reference strains from closely related species of the genus Microvirga. On the basis of genotypic and phenotypic analysis, a novel species named Microvirga ossetica sp. nov. is proposed. The type strain is V5/3M(T) (= LMG 29787(T) = RCAM 02728(T)). Three additional strains of the species are V5/5K, V5/5M and V5/13