Screening of antagonistic potential bacteria from rhizosphere soil against phytopathogenic fungi related to selected vegetable crops

Fungal phytopathogens cause serious losses of crop production worldwide, which causes serious losses of crop production. Bacteria play a role as the biocontrol agents for plant disease control. For this reason, the present study was conducted to determine the antagonistic potential of rhizosphere soil bacteria against selected phytopathogenic fungi. The screenings of potential antagonist isolated bacteria were applied by the dual culture technique with fungi Fusarium oxysporum and Colletotrichum melongenae. Molecular characterization was performed through 16S rDNA sequencing analysis. Sixteen (16) out of fifty (50) isolated bacteria showed different degrees of antagonism (25-67%) against both fungi F. oxysporum and C. melongenae. Among them, four (4) isolated bacteria (isolates A4, C1, C2, and E2) exhibited strong antagonism (more than 50% mycelial growth inhibition) against both fungi. The 16S rDNA sequences of the isolated bacteria A4, C1, C2 and E2 were 99-100% similar to Providencia sp. TT14, Bacillus subtilis 168, Bacillus subtilis RKP-2, and Bacillus amyloliquefaciens IBSDG-11, respectively. Based on the capability for the control of mycelial growth against both fungi, B. subtilis IUBTC2 was selected for optimization of growth characteristics and identification the bioactive metabolites which can enhance plant growth and disease control capacity of plants against the phytopathogenic fungi.