In vitro antagonism and biocontrol effects of Paenibacillus polymyxa JY1-5 against Botrytis cinerea in tomato

• P. polymyxa JY1-5 has the potential to control gray mold disease on tomato. • MALDI-TOF-MS identified a mixture of fusaricidins in the antifungal compounds. • Fusaricidins suppressed spore germination and germ tube elongation. • Fusaricidins damaged the plasma membrane of Botrytis cinerea , leading to the cell leakage. Tomato gray mold caused by Botrytis cinerea is one of the most destructive airborne diseases in tomatoes. In this study, the bacterial strain JY1-5 was isolated from the rhizosphere of turnip and displayed strong antagonistic activity against B. cinerea . This isolate was identified as Paenibacillus polymyxa via analyses of its physiological and biochemical features and partial 16S rRNA sequences. The biological control activity of P. polymyxa JY1-5 against B. cinerea was determined in vitro and in vivo . Both the living cells of JY1-5 and its antifungal compounds strongly reduced the incidence and severity of gray mold disease in tomatoes. Strain JY1-5 grew rapidly in Nutrient broth (NB). Higher amounts of antifungal substances were observed when strain JY1-5 was cultured in Katznelson and Lochhead and potato dextrose broth than in NB or other media tested in this study. The antifungal extracts (FUSE) were determined by MALDI-TOF MS to contain members of the fusaricidin (883, 897, 901, 915, 947, 965, and 979 Da) or LI-F antibiotic (929 Da) family. The antifungal activity of the FUSE was stable in a pH range of 5–7 and at 100 °C for 20 min. Our results showed that the fusaricidin extracts damaged the plasma membrane of B. cinerea , leading to cell leakage and the release of intracellular constituents. Overall, our study suggests that P. polymyxa JY1-5 can potentially be used as a biocontrol agent to manage tomato gray mold disease caused by B. cinerea .