Comparison of Antifungal Activity of Bacillus Strains against Fusarium graminearum In Vitro and In Planta

Fusarium graminearum (Fg) causes Fusarium head blight (FHB) disease in wheat and barley. This pathogen produces mycotoxins including deoxynivalenol (DON), the T-2 and fumorisin B1. Translocation of the mycotoxins in grains causes important losses in yields and contributes to serious health problems in humans and livestock. We tested the Bacillus strains, two commercial, QST713 (Serenade®) and FZB24 (TAEGRO®) and one non-commercial strain EU07 as microbial biological control agents against the F. graminearum strain Fg-K1-4 both in vitro and in planta. The EU07 strain showed better performance in suppressing the growth of Fg-K1-4. Cell-free bacterial cultures displayed significant antagonistic activity on Fg-K1-4. Remarkably, heat and proteinase K treatment of bacterial broths did not reduce the antagonistic activity of Bacillus cultures. DON assays showed that Bacillus strain was not affected by the presence of DON in the media. Leaf and head infection assays using Brachypodium distachyon (Bd-21) indicated that EU07 inhibits Fg-K1-4 growth in vivo and promotes plant growth. Overall, the EU07 strain performed better, indicating that it could be explored for the molecular investigations and protection of cereal crops against FHB disease.