Screening of Antagonistic Strain against Phytophthora capsici and Study on Its Physiological-Biochemical Characteristics

Pepper (Capsicum annuum L.) is rich in flavors and nutrients, it can be eaten fresh and processed, making it an important economic crop. However, pepper phytophthora blight, caused by Phytophthora capsica, is a devastating soil borne disease of peppers, causing a decrease in yield and quality. In this study, biocontrol agent with high antagonistic effect against P. capsici in vivo were screened, and the physiological and biochemical characteristics and bacteriostatic spectrum of this biocontrol strain were studied. The results showed that among the 30 strains of biocontrol bacteria tested, JK2 strain had an in vivo inhibition rate of 90.48% against P. capsici. JK2 grew rapidly within 2-10 hours after inoculation with spore suspension, and can grow at a temperature of 4-50℃, with an optimal growth temperature of 37℃; It exhibits good growth ability at pH 5-10, with an optimal pH of 7, and can grow in environments with strong acidity (pH=3). In addition, the JK2 strain also showed a high inhibition rate against P. sojae (83.88%). Therefore, JK2 is a highly effective biocontrol agent against P. capsici, and the strain has a broad antibacterial spectrum with inhibiting a variety of pathogens, so it has high application value.