Clarification of the Antagonistic Effect of the Lipopeptides Produced by Bacillus amyloliquefaciens BPD1 against Pyricularia oryzae via In Situ MALDI-TOF IMS Analysis

This study tried to clarify the antagonistic effect of the lipopeptides secreted by Bacillus amyloliquefaciens strain BPD1 (Ba-BPD1) against Pyricularia oryzae Cavara (PO). To determine the major antifungal lipopeptides effective against PO, single and dual cultures were carried out in solid-state media. The matrix-assisted laser desorption/ionization–time of flight imaging mass spectrometry (MALDI-TOF IMS) was used to identify the most effective lipopeptide in situ. Meanwhile, the morphology of pathogen fungi treated with lipopeptides was observed via the SEM. Of the three lipopeptide families, surfactin, iturin, and fengycin, the last was identified as the most effective for inhibiting mycelium growth and conidial germination of PO. The conidia and hyphae of fengycin-treated PO were shown to become deformed and tumorous under exposure. This study provides insights into the antagonistic effect of Ba-BPD1 against fungal phytopathogens. Such insights are helpful in the development of reagents for biological control applications.