Identification, Biocontrol Activity, and Field Application Effect of Bacillus velezensis Yb-1

Colletotrichum capsici is one of the most important pathogens on chili peppers. Unreasonable application of chemical fungicides will lead to threats to human and animal health, environmental damage, and increased fungicide resistance to pathogens. As an alternative strategy, biological control has been paid more and more attention by academics. In this study, the Yb-1 strain was isolated from healthy cucumber leaves, which could significantly restrict the mycelium growth of C. capsici and Botrytis cinerea, with inhibition rates of 93.49% and 74.03%, respectively. Strain Yb-1 was identified as Bacillus velezensis by morphological features and 16S rRNA gene, gyrA gene, and gyrB gene sequence analysis. When pepper seeds were treated with different concentrations of bacterial suspension, we found that a medium-concentration treatment (10(4) CFU/mL and 10(5) CFU/mL) could promote seed germination and growth, while high-concentration treatments (10(8) CFU/mL) limited seed germination and growth. In addition, the root-irrigation method, acupuncture-leaf method, and leaf-cutting method were used to evaluate the safety of strain Yb-1 on peppers. The results indicated that Yb-1 did not affect the normal growth of peppers. The results of further field trials showed that the control effect of strain Yb-1 on pepper anthracnose was 59.45%. Thus, the strain B. velezensis Yb-1 has great biocontrol potential for pepper anthracnose and promotes plant growth.