Identification and characterization of the Bacillus atrophaeus strain J-1 as biological agent of apple ring rot disease

Bacillus species are promising agents for the biological control of postharvest diseases. Based on the morphological, physiological and biochemical characteristics and 16S rRNA gene sequence analysis, the bacterial strain J-1 was identified as Bacillus atrophaeus. The B. atrophaeus strain J-1 showed broad spectrum antifungal activity against various plant pathogenic fungi. In assays in vitro the metabolites contained in the B. atrophaeus strain J-1 cell-free filtrate had a strong inhibitory effect on Botryosphaeria dothidea. The cell-free filtrate inhibited the growth of B. dothidea in vivo and reduced the disease incidence. Furthermore, PCR detection showed that the strain J-1 had lipopeptide antibiotic biosynthesis genes: fengycin, iturin A and surfactin. The lipopeptide crude extractions from the strain J-1 cell-free filtrate significantly suppressed the growth of B. dothidea. C14 iturin A was isolated by bioactivity-guided fractionation and identified by liquid chromatography–electronic spray ionization–tandem mass spectrometry analysis. This paper is the first to report that B. atrophaeus J-1 efficiently controls apple ring rot disease caused by B. dothidea. Using the B. atrophaeus strain J-1 may provide an alternative control method for the prevention apple ring rot disease.