Quorum quenching of Bacillus cereus INT1c against Pseudomonas syringae

Abstract

Quorum Quenching is a process to prevent AHL signal accumulation resulting in the virulence factors and pathogenicity genes. The aims of this study were to determine the ability of the AHL (Acil Hocerine Lactone)-lactonase produced by Bacillus cereus INT1c and its potential as a biocontrol agent against Pseudomonas syringae. The experiments were swarming motility inhibition of P. syringae and inhibition assay of P. syringae on snap beans, INT1c produced extracellular and intracellular AHL-lactonase which could inactivate quorum sensing process of C. violaceum. The crude enzymes of INT1c were precipitated optimally at 70% saturation of ammonium sulphate. The Bacillus could reduce rot symptom of snap beans caused by P. syringae and motility of the pathogen. Swarming motility distance of the pathogen on control plates were 12.25 mm while the pathogen was co-cultured with INT1c was 3.3 mm. The average length of rot symptoms on positive control was longer (6.4 cm) than the snap beans inoculated with INT1c (3.92 cm). The population of P. syringae on the snap beans was decreased. Due to nutrient competition between P. syringae and INT1c. These results indicated that INT1c was potentially developed as a biocontrol agent.