Plant host habitat and root exudates shape soil bacterial community structure

Feth el Zahar Haichar, Christine Marol, Odile Berge, J Ignacio Rangel-Castro, James I Prosser, Jérôme Balesdent, Thierry Heulin, Wafa Achouak

Research output: Contribution to journalArticlepeer-review

830 Citations (Scopus)


The rhizosphere is active and dynamic in which newly generated carbon, derived from root exudates, and ancient carbon, in soil organic matter (SOM), are available for microbial growth. Stable isotope probing (SIP) was used to determine bacterial communities assimilating each carbon source in the rhizosphere of four plant species. Wheat, maize, rape and barrel clover (Medicago truncatula) were grown separately in the same soil under (13)CO(2) (99% of atom (13)C) and DNA extracted from rhizosphere soil was fractionated by isopycnic centrifugation. Bacteria-assimilating root exudates were characterized by denaturing gradient gel electrophoresis (DGGE) analysis of (13)C-DNA and root DNA, whereas those assimilating SOM were identified from (12)C-DNA. Plant species root exudates significantly shaped rhizosphere bacterial community structure. Bacteria related to Sphingobacteriales and Myxococcus assimilated root exudates in colonizing roots of all four plants, whwereas bacteria related to Sphingomonadales utilized both carbon sources, and were identified in light, heavy and root compartment DNA. Sphingomonadales were specific to monocotyledons, whereas bacteria related to Enterobacter and Rhizobiales colonized all compartments of all four plants, used both fresh and ancient carbon and were considered as generalists. There was also evidence for an indirect important impact of root exudates, through stimulation of SOM assimilation by a diverse bacterial community.
Original languageEnglish
Pages (from-to)1221-1230
Number of pages10
JournalThe ISME Journal
Issue number12
Early online date28 Aug 2008
Publication statusPublished - Dec 2008


  • Bacteria
  • Carbon Isotopes
  • Ecosystem
  • Molecular Sequence Data
  • Phylogeny
  • Plant Exudates
  • Plant Roots
  • Soil Microbiology


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