Abstract: In order to isolate and identify highly bioactive compounds against anthracnose disease caused by Colletotrichum gloeosporioides in postharvest mangos and to investigate their mechanism of action, bioassay-guided fractionation was used to isolate antifungal substances from the fermented broth of Bacillus megaterium LB01 and the antifungal activity was evaluated by measuring the inhibition zone diameter using the disk diffusion test method. The results showed that four monomeric compounds were separated from the fermented broth, and only one monomer with strong antifungal activity, numbered 001, was obtained and identified as 12-hydroxyjasmonic acid (TA) by electrospray ionization mass spectrometry (ESI-MS), 1H nuclear magnetic resonance (NMR) and 13C NMR analysis. Its mechanism of action was by inducing reactive oxygen production to cause mitochondrial damage, destroy the integrity of spore membrane, and finally significantly inhibit spore germination and mycelium growth. This study confirmed that TA can inhibit the anthracnose disease of postharvest mangos by directly inhibiting the mycelium growth and spore germination of Colletotrichum gloeosporioides, which will provide reference for controlling anthracnose disease in postharvest mangos.

Key words: special environment; Colletotrichum gloeosporioides in postharvest mangos; Bacillus megaterium LB01; 12-hydroxyjasmonic acid; structure identification; resistance mechanism