Antimicrobial cyclic lipopeptides from Bacillus mojovensis B1302 against wheat root rot

Bipolaris sorokiniana is the main pathogen affecting wheat, which can cause major disasters in wheat planting areas. In this study, cyclic lipopeptides (CLP) were extracted from Bacillus mojovensis B1302 and had antimicrobial activity on Bipolaris sorokiniana and other four pathogenic fungi. CLP could inhibit the growth of B. sorokiniana and made mycelia swelling and deformed. In addition, trypan blue staining indicated the distortion of mycelia and DAPI staining showed mycelial DNA damage in the CLP treatment group. Moreover, CLP were effective in controlling wheat root rot with the efficacy of 80.32%, which was not significantly different from that of commercial fungicide (carbendazim). Next, in the oil spreading test, the diffusion diameter of 40 μL CLP (10 mg/mL) reached 8.37 cm with a stable spreading ring, indicating CLP had surface activity. And also, CLP had strong antioxidant capacity and DPPH scavenging activity. Furthermore, CLP had better temperature tolerance at 20–40 °C and pH tolerance at 4–8, respectively, still maintained a high inhibition rate after 3h treatment under UV irradiation, and were stable under trypsin treatment. However, CLP were sensitive to pepsin and metal ions. In conclusion, CLP had antimicrobial activity, antioxidant capacity and environmental tolerance, which had good potential for development into biocontrol agents against wheat root rot.