B579 Controls Cucumber Fusarium Wilt by Improving Rhizosphere Microbial Community.

With continuous improvements in people's environmental awareness, biological control agents have garnered considerable attention owing to their advantageous impacts on improving soil fertility and alleviating plant diseases. () B579, isolated from the rhizosphere soil of cucumber, has effectively suppressed the growth of pathogenic . Our study investigates the effects of B579 on the properties of the rhizosphere soil (its physicochemical properties and enzymatic activities) and microbial community of cucumber under infection. An amplicon sequencing analysis of the microorganisms in the rhizosphere soil was conducted, and the soil's properties were measured. The findings demonstrated that B579 exhibited 73.68% efficacy in controlling cucumber Fusarium wilt disease. B579 pretreatment substantially increased the bacterial and fungi diversity and improved the soil's physicochemical properties (pH level and OC, TN, TP, AK, and AP contents) and enzyme activities, especially those of urease and alkaline phosphatase, which exhibited significant increases of 77.22% and 64.77%, respectively, in comparison to those under the pathogen treatment. Furthermore, the utilization of B579 reduced the abundance of while simultaneously increasing the abundance of beneficial groups, including the , s, , , , , and genera. The RDA showed that the abundance of , , , and in the rhizosphere showed positive correlations with most of the soil properties, whereas abundance was negatively correlated with most of the soil's properties. This study provides novel insights into the disease suppression mechanisms of B579, laying the theoretical foundation for its development as a biocontrol agent.