Identification of strain BCA19 as a potential biological control agent against .

In this study, we aimed to screen potential antagonistic microorganisms against , the causal agent of fire blight. From 127 unknown bacterial isolates tested, 2 bacterial strains (BCA3 and BCA19) were identified to show distinct antagonistic activity against in agar plate assay. Phylogenetic analysis of the 16s rRNA sequence identified both BCA3 and BCA19 as . Among these BCA19 showed 13.9% stronger antagonistic activity than BCA3. Thus we further characterized antagonistic activity of BCA19. Culture filtrates () of BCA19 significantly inhibited the swimming and swarming motility of . Ethyl acetate and n-butanol extracts of of BCA19 exhibited antibacterial activity in disk diffusion assay. Furthermore, gas chromatography-mass spectrometry analysis of ethyl acetate and n-butanol extracts of of BCA19 identified antibacterial compounds, including indole and hexahydropyrrolo[1,2-a]pyrazine-1,4-dione. Importantly, indole inhibited growth of with IC value of 0.109 ± 0.02 mg/mL (~930.4 μM). Whole genome sequence analysis of BCA 19 revealed gene clusters related with siderphore, andrimid, arylpolyene and carotenoid-type terpene production. This study indicates that BCA19 can be used as a potential biological control agent against .