Antagonistic Properties of Lipopeptides and Volatiles Produced by Bacillus subtilis JA

Abstract:

Lipopeptides produced by Bacillus subtilis JA antagonized a broad spectrum of fungal pathogens. Crude lipopeptides were extracted with methanol from the precipitate which was obtained by adding 6 mol/L HCl to the cell-free culture broth. The crude extract was run on Diamonsil C18 column (5 mm, 250 mm×4.6 mm) in reverse phase HPLC system to purify the lipopeptides. Inhibitory ability and IC50 values of lipopeptides towards various microorganisms were determined by agar diffusion method. The results showed lipopeptides exhibited strong inhibitory activity against some important plant pathogenic fungi, including R. solani and F. oxysporum. The ability of B. subtilis JA to antagonize against the growth of the post-harvest pathogen-B. cinerea was tested in vitro. Spore germination of B. cinerea was strongly inhibited in the presence of JA cell suspension. Furthermore, B. subtilis JA can produce antifungal volatiles which strongly inhibited the spore germination and mycelial growth of B. cinerea. As a biocontrol agent, the synergic effect of lipopeptides and volatiles may play a major role in controlling the pathogens by B. subtilis JA.