Antifungal activity and identification of active compounds of Bacillus amyloliquefaciens subsp. plantarum against Botryosphaeria dothidea

Summary The canker disease caused by Botryosphaeria dothidea in China has resulted in serious damage and death to Carya cathayensis and continues to expand its range. A Bacillus strain, designated Bacillus amyloliquefaciens subsp. plantarum CGMCC 11640, was successfully screened from 103 field isolates from local soils by a plate dual-culture method. It showed inhibition zones between B. dothidea and CGMCC 11640 in vitro. From a methyl alcohol extract of the filtrate, the antifungal compounds were identified as a series of lipopeptides by HPLC, namely fengycins, surfactins and iturins, with fengycins being the dominant component. The fengycins were further identified by LC–MS to be a mixture of C15, C16, C17 and C18 fengycin A and their isomers (normal, iso and anteiso). The strong anti-B. dothidea activity indicated that the B. amyloliquefaciens subsp. plantarum CGMCC 11640 and its bioactive components might provide an alternative bioresource for the biocontrol of C. cathayensis canker.