Study on the Inhibitory Effects of Three Endophytic Bacillus Strains on Aspergillus flavus in Maize

Maize is easily contaminated by Aspergillus flavus, and the aflatoxin produced by A. flavus has been classified as a Group 1 carcinogen, for which there are currently no effective control measures. Biological control is regarded as an environmentally friendly and safe approach. Strains ZH179, ZH409, and ZH99 are three bacteria isolated from our laboratory that exhibit antagonistic effects against A. flavus. We conducted experiments to investigate their biocontrol efficacy.

The experimental results demonstrated that these three strains effectively inhibited A. flavus on plates and stored maize seeds. Identification revealed that ZH179 is Bacillus velezensis, while ZH409 and ZH99 are B. amyloliquefaciens. We also identified lipopeptide synthetase-related genes, including srfAA, srfAD, fenA, fenB, ituA, ituB, ituD, bmyA, bmyB, and bmyC, in these three strains. Furthermore, LC-MS analysis confirmed that these strains could produce lipopeptide compounds such as surfactin, fengycin, iturin, and bacillomycin. Using the Oxford cup method, we found that the lipopeptide compounds produced by these strains can inhibit the growth of A. flavus.

These findings suggest that strains ZH179, ZH409, and ZH99 have good control effects on A. flavus during the storage of maize, primarily due to the lipopeptide compounds. This study provides a theoretical basis for using these three strains in the biological control of A. flavus.