African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5210

Full Length Research Paper

Isolation and identification of N-acylhomoserin lactone degrading bacteria from potato rhizosphere

Esmaeil Mahmoudi1*, Nader Hasanzadeh1, Badraldin Ebrahim Sayed Tabatabaei2 and Vittorio Venturi3
1Department of Plant Pathology, Science and Research Branch, Islamic Azad University, Tehran, Iran. 2Department of Biotechnology, Faculty of Agriculture, Isfahan University of Technology, Isfahan, Iran. 3Bacteriology Group, International Center for Genetic Engineering and Biotechnology, Trieste, Italy.
Email: [email protected]

  •  Accepted: 19 May 2011
  •  Published: 04 July 2011


In many Gram-negative bacteria, including a number of pathogens such asPectobacterium carotovorum, virulence factor production and many functions are linked to the quorum sensing (QS) systems that use diffusible N-acyl homoserine lactones (AHLs) as intercellular messenger molecules. A number of organisms also contain genes that hydrolyze AHLs into inactive products, thereby blocking the quorum-sensing systems. In this study, the diversity of bacteria that inactivate N-AHL signal in soil and potato rhizoshere was investigated. Among 139 isolated strains, eighteen N-AHL degrading isolates were finally identified as genera BacillusArthrobacterMesorhizobium,Pseudomonas and Streptomyces using polyphasic approaches. All these isolates were capable to degraded both synthetic and natural N-AHL produced by Pectobacterium atrosepticum strain SM1. In quenching experiments selected isolates, especially Bacillussp. EM84, were markedly reduced the pathogenicity of PaSM1 in potato tubers and totally suppressed tissue maceration on potato tubers. These results reveal the diversity of the QS interfering bacteria in the rhizosphere and demonstrate the validity of targeting QS signal molecules to control pathogens with natural bacterial isolates.


Key words: Quorum sensing, acyl-homoserin lactone, quorum quenching, biocontrol.