Volatile organic compounds of Bacillus cereus strain Bc-cm103 exhibit fumigation activity against Meloidogyne incognita
Bacillus cereus strain Bc-cm103 shows nematicidal activity and therefore has been used as a biological control agent to control the root-knot nematode Meloidogyne incognita. However, it remains unknown whether volatile organic compounds (VOCs) produced by B. cereus strain Bc-cm103 are effective in biocontrol against M. incognita. Therefore, in this study, we investigated the activity of Bc-cm103 VOCs against M. incognita. The B. cereus strain Bc-cm103 significantly repelled the second-stage juveniles (J2s) of M. incognita. In vitro evaluation of VOCs produced by the fermentation of Bc-cm103 in a three-compartment Petri dish revealed the mortality rates of M. incognita J2s as 90.8% at 24 h and 97.2% at 48 h. Additionally, evaluation of the ability of Bc-cm103 VOCs to suppress M. incognita infection in a double-layered pot test showed that root galls on cucumber roots decreased by 46.1%. Furthermore, 21 VOCs were identified from strain Bc-cm103 by solid-phase micro-extraction gas chromatography-mass spectrometry (SPME-GC-MS), including alkanes, alkenes, esters and sulfides. Among them, dimethyl disulfide (30.63%) and S-methyl ester butanethioic acid (30.29%) were reported to have strong nematicidal activity. Together, these results suggest that B. cereus strain Bc-cm103 exhibits fumigation activity against M. incognita.