Biocontrol Efficacy of Bacillus cereus Strain Bc-cm103 Against Meloidogyne incognita

Root-knot nematodes (Meloidogyne spp.) are soilborne pathogens that infect vegetable crops and cause major economic losses worldwide annually. Therefore, there is an urgent need for novel nematicides or biological control agents to reduce the damage caused by root-knot nematodes. In this study, we tested efficacy of the Bacillus cereus strain Bc-cm103, isolated from the rhizoplane of Cucumis metuliferus, against Meloidogyne incognita. Strain Bc-cm103 fermentation broth caused 100% mortality of the nematode second-stage juveniles within 12 h and decreased the egg hatching rate by 40.06% within 72 h compared with sterile water. Confocal laser-scanning microscopy revealed that strain Bc-cm103 formed a biofilm on cucumber (C. sativus) roots, which protected the roots from the infection of M. incognita. Additionally, strain Bc-cm103 activated the defense-responsive genes PR1, PR2, LOX1, and CTR1 in cucumber. Furthermore, strain Bc-cm103 significantly reduced the appearance of root galls in pot, split-root, and field tests. These results indicated that B. cereus strain Bc-cm103 had a strong suppressive effect on M. incognita and therefore could be used as a potential biocontrol agent against this pathogen.

Automated summary

The study demonstrated that Bacillus cereus strain Bc-cm103 isolated from the rhizoplane of Cucumis metuliferus showed strong suppressive effect against Meloidogyne incognita, causing 100% mortality of nematode second-stage juveniles within 12 hours and reducing egg hatching rate by 40.06% within 72 hours compared to the control. Bc-cm103 formed a protective biofilm on cucumber roots, activated defense-responsive genes in cucumber, and significantly reduced root galls in pot, split-root, and field tests, indicating its potential as a biocontrol agent against this pathogen.