Negative Cross-Communication among Wheat Rhizosphere Bacteria: Effect on Antibiotic Production by the Biological Control Bacterium Pseudomonas aureofaciens 30-84
AUTOR(ES)
Morello, J. E.
FONTE
American Society for Microbiology
RESUMO
Phenazine antibiotic production in the biological control bacterium Pseudomonas aureofaciens 30-84 is regulated in part via the PhzR/PhzI N-acyl homoserine lactone (AHL) system. Previous work showed that a subpopulation of the wheat rhizosphere community positively affected phenazine gene expression in strain 30-84 via AHL signals (E. A. Pierson, D. W. Wood, J. A. Cannon, F. M. Blachere, and L. S. Pierson III, Mol. Plant-Microbe Interact. 11:1078-1084, 1998). In the present work, a second subpopulation, one that negatively affected phenazine gene expression, was identified from this rhizosphere community. Strain 30-84 grown in conditioned medium (CM) from several strains produced lower levels of phenazines (1.5- to 9.3-fold) than control when grown in CM from the strain 30-84I1/I2. Growth of the phzB::lacZ reporter strain 30-84Z in this CM resulted in decreased lacZ expression (4.3- to 9.2-fold) compared to growth of the control strain in CM, indicating that inhibition of phzB occurred at the level of gene expression. Preliminary chemical and biological characterizations suggested that these signals, unlike other identified negative signals, were not extractable in ethyl acetate. Introduction of extra copies of phzR and phzI, but not phzI alone, in trans into strain 30-84Z reduced the negative effect on phzB::lacZ expression. The presence of negative-signal-producing strains in a mixture with strain 30-84 reduced strain 30-84's ability to inhibit the take-all disease pathogen in vitro. Together, the results from the previous work on the positive-signal subpopulation and the present work on the negative-signal subpopulation suggest that cross-communication among members of the rhizosphere community and strain 30-84 may control secondary metabolite production and pathogen inhibition.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=404427Documentos Relacionados
- Survival of GacS/GacA Mutants of the Biological Control Bacterium Pseudomonas aureofaciens 30-84 in the Wheat Rhizosphere
- Repression of Phenazine Antibiotic Production in Pseudomonas aureofaciens Strain 30-84 by RpeA
- N-acyl-homoserine lactone-mediated regulation of phenazine gene expression by Pseudomonas aureofaciens 30-84 in the wheat rhizosphere.
- Phenazine antibiotic biosynthesis in Pseudomonas aureofaciens 30-84 is regulated by PhzR in response to cell density.
- phzO, a Gene for Biosynthesis of 2-Hydroxylated Phenazine Compounds in Pseudomonas aureofaciens 30-84