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Front. Microbiol. | doi: 10.3389/fmicb.2019.01456

Nodulation of Retama monosperma by Ensifer aridi in an abandonned lead mine soils in eastern Morocco

  • 1Mohammed V University, Morocco
  • 2Spanish National Research Council (CSIC), Spain

Millions of tons of lead and zinc wastes from the abandoned Toussite mine are stored in the open air as dikes in the vicinity of the villages in Eastern Morocco and pose a real danger to both the environment and local populations. To prevent the movement of minerals to the nearby villages and limit the damages to the environment and health, we proposed the nitrogen-fixing leguminous shrub Retama monosperma, as a model plant to use for phytostabilization experimentations. This plant species is known by its ability to grow in hard climatic conditions and in heavy metals contaminated soils.
The isolation of bacterial strains nodulating R. monosperma in the abandoned mine soils will permit the selection of rhizobia to inoculate young plant seedlings before their use for the phytostabilization of the mine tailings.
In this work, forty-four bacteria were isolated from the root nodules of R. Monosperma grown in the Touissit abandoned mine. Twenty-four isolates were considered as true rhizobia as they possess a copy of the nodC symbiotic gene and were able to renodulate their original host.
The phenotypic characterization showed that all the strains are tolerant in vitro to different concentrations of heavy metals.
The analysis of the 16S rRNA sequences of two selected representative strains showed they were related to different strains of Ensifer aridi isolated from different legumes in three continents deserts. The glnII, recA and gyrB housekeeping genes analysis confirmed the affiliation of the strains to E. aridi. Moreover, the phylogenic analysis of nodA, nodC and nifH symbiotic genes showed that the strains are more related to Ensifer aridi JNVUTP6 species isolated from Tephrosia purpurea root nodules in the Thar Desert in India.
To our knowledge, this is the first report about the isolation of E. aridi from R. monosperma root nodules.

Keywords: Retama monosperma, Phytostabilization, Lead mine waste, Ensifer aridi, nodulation, IDENTIFICATION, Symbiosis, metalic stress

Received: 14 Feb 2019; Accepted: 11 Jun 2019.

Edited by:

Lorena Carro, Newcastle University, United Kingdom

Reviewed by:

Oswaldo Valdes-Lopez, National Autonomous University of Mexico, Mexico
Marcela C. Pagano, Federal University of Minas Gerais, Brazil  

Copyright: © 2019 Missbah El Idrissi, Lamin, Alami, Bouhnik, ElFaik, Abdelmoumen and Bedmar. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Mustapha Missbah El Idrissi, Mohammed V University, Rabat, Morocco,