Screening of antagonistic bacteria CL-1 against banana wilt disease and optimization of fermentation conditions

Microbial strains were isolated from the rhizosphere soil from banana orchard without Fusarium oxysporum f. sp cubense Tropical Race 4（Foc TR4）infection, providing a new option for green prevention and control of banana wilt disease. Rhizosphere soil from banana orchards in Huaqiao University greenhouse was collectted, and dilution coating and plate confrontation methods was used to screen for excellent antagonistic strains, and optimize the growth conditions. The results showed that three antagonistic strains were isolated, among which CL-1 strain had the best antagonistic effect, with inhibition rate of 34.25%. The 16S RNA sequencing results indicated that the strain had a similarity of 99.38% with Stenotrophomonas maltophilia, and was preliminarily identified as Stenotrophomonas maltophilia. Single factor cultivation conditions were optimized for strain CL-1, and the optimal culture medium for CL-1 strain was beef extract 5 g·L⁻¹, peptone 10 g·L⁻¹, and calcium chloride 5 g·L⁻¹. After optimization, the inhibition rate increased to 45.21%. The CL-1 strain can effectively inhibit the growth of banana Foc TR4 and has good biocontrol potential.