2.1. Isolation of antagonistic bacteria
Antagonistic bacteria were isolated from the rhizospheric soil of tomato plants in Henan Province, China. The soil sample (5 g) was shaken in 100 ml sterilized water for 20 min. The soil suspension was then serially diluted and spread on King's B agar (King et al. 1954). After incubating at 30 °C for 2 days, single bacterial colonies were selected and streaked onto a new LB (Luria–Bertani) plate. The purified colonies were preserved in LB medium containing 10% glycerol at −80 °C.