Butyl succinate-mediated control of Bacillus velezensis CE 100 for apple anthracnose caused by Colletotrichum gloeosporioides

Aims Microbial biocontrol agents have become an effective option to mitigate the harmfulness of chemical pesticides in recent years. This study demonstrates the control efficacy of Bacillus velezensis CE 100 on the anthracnose causal agent, Colletotrichum gloeosporioides.Methods and results In vitro antifungal assays revealed that the culture filtrate and volatile organic compounds of B. velezensis CE 100 strongly restricted the mycelial development of C. gloeosporioides. Moreover, a bioactive compound, butyl succinate, was isolated from the n-butanol crude extract of B. velezensis CE 100 (bce), and identified by liquid chromatography-electrospray ionization hybrid ion-trap and time-of-flight mass spectrometry (LC-ESI-QTOF-MS) and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR). Treatment with purified butyl succinate at a concentration of 300 mu g mL-1 strongly controlled conidial germination of C. gloeosporioides with an inhibition rate of 98.66%, whereas butyl succinate at a concentration of 400 mu g mL-1 showed weak antifungal action on the mycelial growth of C. gloeosporioides with an inhibition rate of 31.25%. Scanning electron microscopy revealed that the morphologies of butyl succinate-treated hyphae and conidia of C. gloeosporioides were severely deformed with shriveled and wrinkled surfaces. Furthermore, butyl succinate was able to control carbendazim-resistant C. gloeosporioides, demonstrating that it could be a promising agent for the suppression of other carbendazim-resistant fungal pathogens. An in vivo biocontrol assay demonstrated that the strain ce 100 broth culture and butyl succinate showed higher control efficacy on apple anthracnose than bce.Conclusions Our findings provide insight into the antifungal potential of B. velezensis ce 100 and its butyl succinate for efficient control of phytopathogenic fungi, such as C. gloeosporiodes, in plant disease protection. This is the first study to demonstrate the antifungal potential of bacteria-derived butyl succinate for control of C. gloeosporioides.

Automated summary

This study demonstrates the control efficacy of Bacillus velezensis CE 100 and its bioactive compound butyl succinate on the anthracnose causal agent, Colletotrichum gloeosporioides. The culture filtrate and volatile organic compounds of B. velezensis CE 100 strongly restricted the mycelial development of C. gloeosporioides. In addition, purified butyl succinate showed strong control on conidial germination of C. gloeosporioides, and could also control carbendazim-resistant strains of the pathogen.