文摘
Bacillus subtilis inhibits growth of plant pathogen and causes mortality of plant pests by producing lipopeptide biosurfactans. In this study secondary metabolites produced by Bacillus subtilis mutant M419 was extracted and production of lipopeptide surfactants of the mutant was observed by hemolytic activity and oil spreading techniques. The effects of the biosurfactant on mortality of the first and second instars of Papilio demoleus Linnaeus was evaluated by leaves immersion method at 3600, 1800, 900, 450 and 0 mg/l concentrations in laboratory. The LC50 and LC90 values after 4 days of contact were measured 1172.145 mg/l and 3336.999 mg/l, respectively. Results indicated that, these values were 3.8-fold and 1.62-fold lower than that obtained after 2 and 3 days, respectively. The crude biosurfactant retained the larvicidal activity even when autoclaved at 121 °C for 15 min. B. subtilis M419 was able to inhibit considerably Aspergillus flavus growth in a dual culture assay.
