CR% values and titers of surfactin.

The parent strain and 37 positive mutants were cultivated in 250 mL Erlenmeyer flask containing 50 mL LB medium aerobically at 37°C and 200 rpm for 24 h, and each strain was incubated in triple. For CR% test, 150 µL supernatant of culture and 75 µL PDA vesicles were reacted in 96-well plate at 25°C for 10 min.