Bacillus species are widely exploited as biocontrol agents because of their efficiency in impeding various plant pathogens with multifaceted approach. In this study, Bacillus species were isolated from rhizosphere of various plants viz., carnations, cotton, turmeric, and bananas in Tamil Nadu state of India. Their potential to control the growth of Sclerotinia sclerotiorum was assessed in vitro by dual plate and partition plate techniques. B. amyloliquefaciens strain VB7 was much effective in inhibiting mycelial growth (45% inhibition of over control) and sclerotial production (100%). PCR detection of AMP genes revealed that B. amyloliquefaciens (VB7) had a maximum of 10 diverse antibiotic biosynthesis genes, namely, ituD, ipa14, bacA, bacD, bamC, sfP, spaC, spaS, alba, and albF, that resulted in production of the antibiotics iturin, bacilysin, bacillomycin, surfactin, subtilin and subtilosin. Further, metabolites from B. amyloliquefaciens strains VB2 and VB7, associated with inhibition of S. sclerotiorum, were identified as phenols and fatty acids by gas chromatography mass spectrometry (GC-MS). Delivery of liquid formulations of the effective strains of Bacillus spp. as root dip was found promising for the management of stem rot of cultivated carnations. Minimal percent disease incidence (4.6%) and maximum plant growth promotion was observed in the plants treated with B. amyloliquefaciens (VB7).

Bacillus subtilis strain BSCBE4 and Pseudomonas chlororaphis strain PA23 ( /P. aureofaciens) were effective biocontrol agents against Pythium aphanidermatum , the causal agent of damping- off of hot pepper (Capsicum annum L.) in greenhouse vegetable production systems. Application of strains BSCBE4 and PA23 at the rate of 20 g kg1 of seed significantly increased the growth of hot pepper seedlings. The efficacies of various carriers in sustaining the population of these strains in storage were assessed. Both the antagonists survived up to 180 days of storage in peat and talc-based formulations. The two bacterial strains induced development of plant defence- related enzymes including phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, phenol content, suppressed incidence of damping-off and increased growth of hot pepper seedlings.

Bacillus subtilis (BSCBE4), Pseudomonas chlororaphis (PA23), endophytic P. fluorescens (ENPF1) inhibited the mycelial growth of stem blight pathogen Corynespora casiicola (Berk and Curt)Wei under in vitro. All these bacterial isolates produced both hydroxamate and carboxylate type of siderophores. But the siderophore production was maximum with the isolate ENPF1. Delivering of talc based formulation of BSCBE4 through seedling dip and foliar application effectively reduced stem blight disease incidence and increased the dry matter production under pot culture and field conditions. Application of BSCBE4, PA23 and ENPF1 increased the defense related enzymes such as peroxidase, polyphenol oxidase, chitinase and β-1,3 glucanase in P. amarus up to ten days after challenge inoculation with C. cassicola. Native gel electrophoretic analysis revealed that challenge inoculation of pathogen with BSCBE4 and PA23 induced both peroxidase and polyphnol oxidase isoforms.