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Microbe-Mediated Processes in Soils

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Front. Environ. Sci. | doi: 10.3389/fenvs.2018.00139

Diversifying anaerobic respiration strategies to compete in the rhizosphere

  • 1UMR5557 Ecologie Microbienne (LEM), France
  • 2CEA Cadarache, France
  • 3Microbial Ecology, France

The rhizosphere is the interface between plant roots and soil where intense, varied interactions between plants and microbes influence plants’ health and growth through their influence on biochemical cycles, such as the carbon, nitrogen and iron cycles. The rhizosphere is also a changing environment where oxygen can be rapidly limited and anaerobic zones can be established. Microorganisms successfully colonize the rhizosphere when they possess specific traits referred to as rhizosphere competence. Anaerobic respiration flexibility contributes to the rhizosphere competence of microbes. Indeed, a wide range of compounds that are available in the rhizosphere can serve as alternative terminal electron acceptors during anaerobic respiration such as nitrates, iron, carbon compounds, sulfur, metalloids and radionuclides. In the presence of multiple terminal electron acceptors in a complex environment such as the rhizosphere and in the absence of O2, microorganisms will first use the most energetic option to sustain growth. Anaerobic respiration has been deeply studied, and the genes involved in anaerobic respiration have been identified. However, aqueous environment and paddy soils are the most studied environments for anaerobic respiration, even if we provide evidence in this review that anaerobic respiration also occurs in the plant rhizosphere. Indeed, we provide evidence by performing a BLAST analysis on metatranscriptomic data that genes involved in iron, sulfur, arsenate and selenate anaerobic respiration are expressed in the rhizosphere, underscoring that the rhizosphere environment is suitable for the establishment of anaerobic respiration. We thus focus this review on current research concerning the different types of anaerobic respiration that occur in the rhizosphere. We also discuss the flexibility of anaerobic respiration as a fundamental trait for the microbial colonization of roots, environmental and ecological adaptation, persistence and bioremediation in the rhizosphere. Anaerobic respiration appears to be a key process for the functioning of an ecosystem and interactions between plants and microbes.

Keywords: rhizosphere competence, anaerobic respiration, Terminal electron acceptors, Respiratory pathways, rhizobacteria, root colonization, adaptation

Received: 27 Sep 2018; Accepted: 01 Nov 2018.

Edited by:

Luiz Fernando W. Roesch, Federal University of Pampa, Brazil

Reviewed by:

Alice Checcucci, Università degli Studi di Firenze, Italy
Rosa M. Martínez-Espinosa, University of Alicante, Spain  

Copyright: © 2018 Lecomte, ACHOUAK, Abrouk, Heulin, Nesme and Haichar. 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: Dr. Feth-el-zahar Haichar, Microbial Ecology, Villeurbanne, France, zahar.haichar@univ-lyon1.fr