Isolation, identification, and biocontrol effect of a bacterial strain HSL3-29 against Colletotrichum musae

Abstract:

[Background] Banana anthracnose is a fungal disease caused by Colletotrichum musae, which seriously restricts the development of the banana industry. [Objective] To screen the biocontrol bacteria against Colletotrichum musae from mangrove soil samples in Guangxi Zhuang Autonomous Region, and evaluate the biocontrol effect of the fermentation broth. [Methods] The biocontrol bacteria were isolated by dilution plate method, and a plate confrontation experiment was conducted to screen out the strains with antagonistic effects on C. musae. The bacterial strain was identified based on morphological characteristics, physiological and biochemical properties, and 16S rRNA sequencing results. The biological characteristics of the strain screened out were studied by single factor experiments. The antagonistic activity was evaluated based on the mycelial growth rate. The biocontrol effect of the fermentation broth was examined with detached banana. [Results] A strain HSL3-29 was isolated from mangrove soil. It had a strong antagonistic effect against C. musae, with the inhibition rate of 81.83%. HSL3-29 had a broad antimicrobial spectrum, with inhibitory effects on other six plant pathogenic fungal species. HSL3-29 was identified as Bacillus amyloliquefaciens. The strain entered the logarithmic growth stage during 4–24 h. It was sensitive to ampicillin and vancomycin, had tolerance to high temperatures, and could survive in high salt environments. The fermentation broth of the strain showed the biocontrol effect up to 39.4% on the banana fruits infected with anthracnose. [Conclusion] A strain of B. amyloliquefaciens with strong antagonism to C. musae was isolated, which provided strain resources for the development of biocontrol agents for banana anthracnose.