The siderophore-producing bacterium, Bacillus siamensis Gxun-6, has an antifungal activity against Fusarium oxysporum and promotes the growth of banana

Background Fusarium wilt of banana is a soil-borne disease caused by Fusarium oxysporum formea speciales (f.sp.) cubense with the Tropical Race 4 (FOC TR4), which seriously restricts the development of the banana industry. The utilization of antagonistic microorganisms to inhibit the propagation of pathogens has become a hot research topic in the field of biological prevention and control because of its green and efficient advantages. Results In this study, 60 siderophore strains from banana rhizosphere soil were screened. Three strains showing antifungal activity were screened out using FOC TR4 as the antagonistic pathogen. Among them, the strain Gxun-6 showed the highest antifungal activity, of up to 68.8%. It also showed significant inhibitory effect on the other 8 plant pathogens tested, thereby demonstrating broad-spectrum antifungal activity. Combined with colony morphology, physiological and biochemical analysis, and 16S rRNA evolutionary tree analysis, Gxun-6 was identified as Bacillus siamensis. Pot experiments showed that this strain had remarkable Fusarium wilt prevention and growth-promoting effect on banana. The control effect can reach 88.26%. The fresh weight increased by 25.36%. Conclusions The strain had strong Fusarium wilt control and growth promoting effects on banana and can be used as a strain resource for developing banana.