Identification of the endosymbionts from Sulla spinosissima growing in a lead mine tailings in Eastern Morocco as Mesorhizobium camelthorni sv. aridi

Abstract

Aims To identify the bacteria nodulating Sulla spinosissima growing profusely in a lead and zinc mine tailings in Eastern Morocco. Methods and Results In all, 32 rhizobial cultures, isolated from root nodules of S. spinosissima growing in soils of the mining site, were tolerant to different heavy metals. The ERIC‐polymerase chain reaction (PCR) fingerprinting analysis clustered the isolates into seven different groups, and the analysis of the 16S rRNA sequences of four selected representative strains, showed they were related to different species of the genus Mesorhizobium. The atpD, glnII and recA housekeeping genes analysis confirmed the affiliation of the four representative strains to Mesorhizobium camelthorni CCNWXJ40‐4T, with similarity percentages varying from 96·30 to 98·30%. The sequences of the nifH gene had 97·33–97·78% similarities with that of M. camelthorni CCNWXJ40‐4T; however, the nodC phylogeny of the four strains diverged from the type and other reference strains of M. camelthorni and formed a separated cluster. The four strains nodulate also Astragalus gombiformis and A. armatus but did not nodulate A. boeticus, Vachellia gummifera, Prosopis chilensis, Cicer arietinum, Lens culinaris, Medicago truncatula, Lupinus luteus or Phaseolus vulgaris. Conclusions Based on similarities of the nodC symbiotic gene and differences in the host range, the strains isolated from S. spinosissima growing in soils of the Sidi Boubker mining site may form a different symbiovar within Mesorhizobium for which the name aridi is proposed. Significance and Impact of the Study In this work, we show that strains of M. camelthorni species nodulating S. spinosissima in the arid area of Eastern Morocco constitute a distinct phylogenetic clade of nodulation genes; we named symbiovar aridi, which encompasses also mesorhizobia from other Mediterranean desert legumes.

Impact of Marine Aquaculture on the Microbiome Associated with Nearby Holobionts: The Case of Patella caerulea Living in Proximity of Sea Bream Aquaculture Cages

“…Its decrease in limpets growing in adhesion to the aquaculture cage might be related to the increase in heavy metal accumulation that often accompanies aquaculture practices [ 1 ], which can indirectly affect the most sensitive species in the microbiome of nearby wild organisms. Conversely, among the discriminant OTUs enriched in the microbiome of limpets collected on the aquaculture cage, we could find two OTUs putatively assigned to environmental bacteria that are instead reported as able to tolerate heavy metal pollution, namely Acinetobacter guillouie and Mesorhizobium camelthorni [ 70 , 71 ].…”

Guidelines for the description of rhizobial symbiovars

“…hedysari [ 53 ] and some months later as sv. aridi [ 54 ]. In this case, considering priority for the date of definition, we should maintain hedysari and consider aridi as a later synonym.…”

Population genomics of Australian indigenous Mesorhizobium reveals diverse nonsymbiotic genospecies capable of nitrogen-fixing symbioses following horizontal gene transfer

“…Mesorhizobium strains can establish nitrogen-fixing symbioses with legume species from temperate, tropical, sub-tropical and arctic areas [2]. These include cultivated legumes such as Lotus spp., Biserrula pelecinus [3,4] and Cicer spp., [5] and a variety of uncultivated legumes [6][7][8][9][10] including Robinia [11], Carmichaelia [7], Acacia and Sesbania [12].…”