This study was conducted to elucidate the possible mechanisms responsible for the biocontrol of southern blight and the elements involved in tomato growth promotion by selected rhizobacteria. The rhizobacteria were characterized by carbon source utilization, fatty acid profiles, and 16S rDNA sequencing, while biocontrol mechanisms were investigated using biochemical indicators and bioassays. The rhizobacteria clustered within Agrobacterium and Kluyvera. The results indicated that iron competition and antibiosis are mechanisms that explain the biocontrol capability of southern blight by rhizobacteria. In the same way, auxin production and biological nitrogen fixation can explain growth promotion. Limitations of biological control were demonstrated because the competition capability is strain-specific for Sclerotium rolfsii, and antibiosis depends on the nutritional composition of growth media.
Athelia rolfsii; Sclerotium rolfsii; antibiosis; auxins; biocontrol; nitrogen fixation; siderophores
