Identification of Two Bacillus Strains with Antimicrobial Activity and Preliminary Evaluation of Their Biocontrol Efficiency

Cabbage Fusarium Wilt (CFW) is a serious disease caused by Fusarium oxysporum f. sp. conglutinans in many parts of the world. The use of chemical fungicides has placed a heavy burden on the environment and is prone to drug resistance in plant pathogens. As a method with great potential, biological control has attracted the attention of many academics both at home and abroad. In this study, we have found that strains B5 and B6 had a strong inhibitory effect on various pathogens and significantly inhibited mycelium growth. They were both identified as Bacillus velezensis by morphological features, biochemical determinations, 16S rRNA gene and gyrA gene sequence analysis. When different concentrations of bacterial suspension were applied to cabbage seeds, hypocotyl and taproot length increased to varying degrees. The in vivo results showed that B5 and B6 decreased the incidence of cabbage seedling wilt disease, with B6 performing significantly better. Furthermore, B. velezensis B6 had the ability to colonize cabbage plants and rhizosphere soil. Thus, strain B6 has great potential for biocontrol development and this research could lead to the development of a promising biological agent for CFW.

Automated summary

This study found that strains B5 and B6 had strong inhibitory effects on various pathogens and significantly inhibited mycelium growth. They were identified as Bacillus velezensis through morphological features, biochemical determinations, and gene sequence analysis. Applying different concentrations of the bacterial suspension to cabbage seeds resulted in increased hypocotyl and taproot length. The in vivo results showed that B6 had better performance in reducing the incidence of cabbage seedling wilt disease. Furthermore, B6 had the ability to colonize cabbage plants and rhizosphere soil.