Inhibitory Effect of Lipopeptide Secreted by Bacillus Strain FJAT-2349 Against Anthracnose Pathogen

  Objective  Inhibitory effect of lipopeptides secreted by Bacillus FJAT-2349 on the pathogen of anthracnose was investigated.

  Method  Agar plate diffusion and pin-prick inoculation were used to determine the inhibition effect of the lipopeptides on the pathogen. The fungal morphology was observed under a scanning and a transmission electron microscope.

  Result  The lipopeptide-producing B. amyloliquefaciens FJAT-2349 could effectively inhibit the growth of Colletotrichum acutatum with an inhibition rate of 87.8%. The lipopeptides were composed of mainly fengycin, but also iturin and surfactin. The diameter of inhibition zone on the agar plate by the lipopeptide against C. acutatum was up to 22 mm. The effect was dose-dependent. Under the electron microscopes, the fungal hyphae appeared deformed and cell walls damaged by the lipopeptides. Inoculation of FJAT-2349 on harvested loquats could delay the onset of anthracnose by one day. The in vivo tests showed that on the 4^th day after inoculation the relative biocontrol efficacy on a curative-treatment group was 29.2% and 72.7% on a preventive-treatment group; and the average lesion diameter on the treatment groups was 4.67-5.00 mm, as opposed to the larger 6.89-7.25 mm of control.

  Conclusion  The lipopeptides secreted by B. amyloliquefaciens FJAT-2349 could effectively inhibit the growth of Colletotrichum acutatum.