In vitro Antagonistic Effects of Plant Growth-Promoting Bacillus spp. Isolated from Talinum fruticosum on Fusarium oxysporum

This study investigated the in vitro antagonistic effect of plant growth-promoting rhizobacteria, Bacillus spp., isolated from Talinum fruticosum, a plant known for its therapeutic and dietary value against the phytopathogenic fungus Fusarium oxysporum. The antagonistic potential of these Bacillus spp. was assessed through in vitro assays, including dual-culture techniques and antimicrobial tests. Results revealed that of all the bacterial isolates identified via cultural and biochemical methods which were then confirmed through molecular analysis with over 99% sequence similarity, Bacillus subtilis exhibited the most significant plant growth-promoting (PGP) traits, testing positive for phosphate solubilization, indole acetic acid production, ammonia production, and nitrogen fixation. This highlights its potential as an effective agent for enhancing plant growth in rhizosphere applications. The in vitro antagonistic potential of Bacillus subtilis against the pathogenic fungus Fusarium oxysporum, with Bacillus subtilis showing a peak inhibition rate of 46.43% at 48 hours. These findings underscore the promising role of Bacillus subtilis as a biological regulator agent that can militate against Fusarium oxysporum, offering a sustainable alternative to chemical control methods for managing plant diseases. Further field trials are recommended to validate these in vitro results and to explore the practical applications of these isolates in sustainable agriculture.