LAUSR

Abstract This study describes the purification, identification and antifungal characterization of Cyclo ( D -PRO- L - VAL) isolated for the first time from Bacillus amyloliquefaciens Y1 (Y1) against Fusarium graminearum. In primary screening, Y1 inhibited more than 50% growth of F. graminearum in dual culture and volatile assay. Similarly, the treatment of wheat grains with crude extract delayed the growth of F. graminearum. Cyclo ( D -PRO- L - VAL) was purified from crude extract using chromatographic techniques and identified by H1 and C13 nuclear magnetic resonance. This compound showed potent antifungal activity against F. graminearum. The minimum inhibitory concentration of Cyclo ( D -PRO- L - VAL) to inhibit any visible mycelial growth of F. graminearum was 250 µg ml-1. The microscopic study revealed alterations of hyphae like deformation, lysis or degradation of F. graminearum after the addition of Cyclo ( D -PRO- L - VAL) in fungal suspension. Moreover, growth of F. graminearum on wheat grains was completely inhibited by 1000 ppm concentration of Cyclo ( D -PRO- L - VAL) after incubation for 10 days. B. amyloliquefaciens Y1 may be a promising alternative to chemical fungicides due to production of Cyclo ( D -PRO- L - VAL) and other antifungal compounds as secondary metabolites to prevent growth of F. graminearum in wheat grains to control head blight and other post-harvest diseases.