Potential of Bacillus amyloliquefaciens for Biocontrol of Bacterial Wilt of Tomato Incited by Ralstonia solanacearum

Fifty seven rhizobacteria were isolated from rhizospheric soil of wilted tomato plants and among them two strains of rhizobacteria, having better antagonistic and plant growth promoting ability were characterized them as Bacillus amyloliquefaciens DSBA-11 and DSBA-12 based on morphological, biochemical, partial gene sequence analysis of 16S rRNA and fatty acid methyl ester analysis. Antagonistic activity of these strains DSBA-11, DSBA-12 was compared with other Bacillus species such as B. subtilis DTBS-5, B. cereus JHTBS-7, B. pumilus MTCC-7092 strains, against Ralstonia solanacearum race 1, bv 3, phylotype I, inciting bacterial wilt of tomato underin vitro conditions. B. amyloliquefaciens DSBA-11 showed maximum growth inhibition of R. solanacearum (4.91cm 2 ) followed by strains DSBA-12 (3.31cm 2 ) and B. subtilis (3.07 cm 2 ). Moreover, strains DSBA-11 was also have better phosphorus solubilizing ability (42.6 g/ml) and indole acetic acid (95.4 g/ml) production than other strains of Bacillus spp. in vitro conditions. Biocontrol efficacy and plant growth ability of these bacterial antagonists was tested against bacterial wilt of tomato cv. Pusa Ruby under glasshouse conditions. Minimum bacterial wilt disease incidenceincultivar Pusa Ruby (17.95%) was recorded in B. amyloliquefaciens DSBA-11followed by B. amyloliquefaciens DSBA-12 after 30 days of inoculation.The bio-control efficacy was higher in B. amyloliquefaciens DSBA -12 treated plants, followed by B. pumilus MTCC-7092.