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

Abstract

Three bacterial strains, LmiM8 T , LmiE10 and LluTb3, isolated from nitrogen-fixing nodules of Lupinus micranthus (Lmi strains) and L. luteus (Llu strain) growing in Northern Tunisia were analysed using genetic, phenotypic and symbiotic approaches. Phylogenetic analyses based on rrs and concatenated gyrB and dnaK genes suggested that these Lupinus strains constitute a new Microvirga species with identities ranging from 95 to 83% to its closest relatives Microvirga makkahensis, M. vignae, M. zambiensis, M. ossetica, and M. lotononidis. The genome sequences of strains LmiM8 T and LmiE10 exhibited pairwise Average Nucleotide Identities (ANIb) above 99.5%, significantly distant (73-89% pairwise ANIb) from other Microvirga species sequenced (M. zambiensis and M. ossetica). A phylogenetic analysis based on the symbiosis-related gene nodA placed the sequences of the new species in a divergent clade close to Mesorhizobium, Microvirga and Bradyrhizobium strains, suggesting that the M. tunisiensis strains represent a new symbiovar different from the Bradyrhizobium symbiovars defined to date. In contrast, the phylogeny derived from another symbiosis-related gene, nifH, reproduced the housekeeping genes phylogenies. The study of morphological, phenotypical and physiological features, including cellular fatty acid composition of the novel isolates demonstrated their unique profile regarding close reference Microvirga strains. Strains LmiM8 T , LmiE10 and LluTb3 were able to nodulate several Lupinus spp. Based on genetic, genomic and phenotypic data presented in this study, these strains should be grouped within a new species for which the name Microvirga tunisiensis sp. nov. is proposed (type strain LmiM8 T = CECT 9163 T , LMG 29689 T).

Characterization of Bradyrhizobium spp. Nodulating Lupinus cosentinii and L. luteus Microsymbionts in Morocco

“…for a long time until Ardley et al (2012) reported the isolation and identification of three symbiotic Microvirga species from L. texensis and Listia angolensis root nodules. More recently, lupines were found to be nodulated by Microvirga strains in Tunisian, Moroccan, and American soils (Beligala et al, 2017;Msaddak et al, 2017Msaddak et al, , 2019Rejili et al, 2019;Missbah El Idrissi et al, 2020). Msaddak et al (2017) suggested that lupines would prefer Bradyrhizobium spp.…”

Pollution pressure drives microbial assemblages that improve the phytoremediation potential of heavy metals by Ricinus communis

“…In contrast, the rhizobiome in GT0 was rich in microorganisms involved in significant processes commonly found in soil see Fig 2 . For example, certain species of bacteria promote plant growth, such as Methylobacterium soli (2%) and Microvirga ossetica (2%) (Chauhan et al 2015;Msaddak et al 2019). Furthermore, other bacteria play a role in the nitrogen cycle, such as Nitrososphaerales archaeon (2%) and Nitrosocosmicus oleophilus (1%), both of which contribute towards ammonia oxidation, as well as Nitrobacter vulgaris, which is a nitrite-oxidizing bacteria (1%) and Hyphomicrobium sp (9%) a denitrification bacterium that participate in the conversion of nitrates into nitrogen gas (Urakami).…”

Microvirga roseola sp. nov. and Microvirga lenta sp. nov., isolated from Taklamakan Desert soil

“…The genus Microvirga , proposed by Kanso and Patel in 2003 [1], belongs to the family Methylobacteriaceae , order Rhizobiales , class Alphaproteobacteria [2]. Members of Microvirga are widely distributed in nature, and have been isolated from various environments, including deep subsurface [1], soil [3, 4], forest soil [5], metal industry waste soil [6], desert soil [7], root nodule [8, 9], hot spring sediments [10], and human healthy skin [11]. Bacteria of this genus are important in soil and possess multiple ecological functions and application potentials [12, 13].…”