Microvirga makkahensis sp. nov., and Microvirga arabica sp. nov., isolated from sandy arid soil

Abstract

The taxonomic positions of two Gram-negative strains, SV1470(T) and SV2184P(T), isolated from arid soil samples, were determined using a polyphasic approach. Analysis of the 16S rRNA gene and the concatenated sequences of three housekeeping gene loci (dnaK, rpoB and gyrB) confirmed that the strains belong to the genus Microvirga. Strain SV1470(T) was found to be closely related to Microvirga vignae BR3299(T) (98.8 %), Microvirga flocculans TFB(T) (98.3 %) and Microvirga lupini Lut6(T) (98.2 %), whilst similarity to other type strains of the genus ranged from 97.8 to 96.3 %; strain SV2184P(T) was found to be closely related to Microvirga aerilata 5420S-16(T) (98.0 %), Microvirga zambiensis WSM3693(T) (97.8 %) and M. flocculans ATCC BAA-817(T) (97.4 %), whilst similarity to other type strains of the genus ranged from 97.2 to 95.9 %. The G + C content of the genomic DNA was determined to be 61.5 mol % for strain SV1470(T) and 62.1 mol % for strain SV2184P(T). Both strains were found to have the same quinone system, with Q-10 as the major ubiquinone. The polar lipid profile of strain SV1470(T) was found to consist of phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid and one unidentified aminolipid, while that of strain SV2184P(T) consisted of phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, one unidentified aminolipid, one unidentified aminophospholipid and two unidentified phospholipids. DNA-DNA relatedness studies showed that the two strains belong to different genomic species. The strains were also distinguished using a combination of phenotypic properties. Based on the genotypic and phenotypic data, the novel species Microvirga makkahensis sp. nov. (type strain SV1470(T) = DSM 25394(T) = KCTC 23863(T) = NRRL-B 24875(T)) and Microvirga arabica sp. nov. (type strain SV2184P(T) = DSM 25393(T) = KCTC 23864(T) = NRRL-B 24874(T)) are proposed.

Diverse Bacteria Affiliated with the Genera Microvirga, Phyllobacterium, and Bradyrhizobium Nodulate Lupinus micranthus Growing in Soils of Northern Tunisia

“…Microvirga colonies were pink in color after 8 days in YMA, as has been observed for other Microvirga strains, such as M. subterranea (20), M. lupini (15), and M. makkahensis (22). The growth rates of bradyrhizobial isolates from groups III and IV were similar to those of B. valentinum and B. retamae, respectively, with an extra-low growth rate phenotype on YMA plates.…”

“…from arid and semiarid alkaline deserts, also in northern China (54). Since Microvirga strains have also been found in arid soils from other areas (22), the capacity to proliferate in arid soils may be an important feature of the symbiosis between Microvirga and L. micranthus in the semiarid soils of Tunisia.…”

“…BSC39 (three copies) (35)(36)(37). Therefore, a different housekeeping gene marker, gyrB, commonly used with Microvirga species (15,21,22), was selected for amplicon characterization. Sequencing of gyrB amplicons confirmed the affiliation of the 20 isolates in group VII to the Microvirga genus (Fig.…”

Microvirgasp. symbiovar mediterranense nodulatesLupinus cosentiniigrown wild in Morocco

“…To confirm the taxonomic status of the L. cosentinii-isolated strains, phylogenetic trees based on the housekeeping concatenated 16S rRNA, dnaK, gyrB and recA sequences were built. The sequences of those genes have been used previously for identification of Microvirga (Ardley et al 2012;Radl et al 2014;Veyisoglu et al 2016;Msaddak et al 2017aMsaddak et al , 2017bRejili et al 2019). The results showed that the isolates from L. cosentinii belong to genus Microvirga and that LmiE10 and LmiM8 isolated from L. micranthus are the closest relative strains based on phylogenies of housekeeping genes.…”

Microvirga tunisiensis sp. nov., a root nodule symbiotic bacterium isolated from Lupinus micranthus and L. luteus grown in Northern Tunisia

“…The same authors obtained a collection of 43 isolates of L. luteus from the same region, out of which 41 belonged to the genus Bradyrhizobium and just two to Microvirga [26]. The genus Microvirga currently comprises eighteen species [1,4,11,13,20,21,27,30,33,34,[37][38][39], of which only four have been described as effective root nodule bacteria: M. lotononidis and M. zambiensis isolated from Listia angolensis nodules [4], M. lupini, from Lupinus texensis [4] and M. vignae from Vigna unguiculata [27]. Through in-depth analysis of genetic, genomic and phenotypic data, we show here that Microvirga strains isolated from the root nodules of Northern Tunisian L. micranthus and L. luteus plants are representatives of a new symbiotic species that we propose to designate as Microvirga tunisiensis.…”