Suppressing Envinia carotovora Pathogenicity by Projecting N-Acyl Homoserine Lactonase onto the Surface of Pseudomonas putida Cells

N-Acyl homoserine lactones (AHLs)serve as the vital quorum-sensing signals that regulate the virulence of the pathogenic bacterium Erwinia carotovora. In the present study, an approach to efficiently restrain the pathogenicity of E. earotovora-induced soft rot disease is described. Bacillus thuringiensis-derived N-acyl homoserine lactonase (AiiA) was projected onto the surface of Pseudomonas putida cells, and inoculation with both strains was challenged. The previously identified N-terminal moiety of the ice nucleation protein, InaQ-N, was applied as the anchoring motif. A surface display cassette with inaQ-N/aiiA was constructed and expressed under the control of a constitutive promoter in P putida AB92019. Surface localization of the fusion protein was confirmed by Western blot analysis, flow cytometry, and immunofluorescence microscopy. The antagonistic activity of P putida MB116 expressing InaQ-N/AiiA toward E. carotovora ATCC25270 was evaluated by challenge inoculation in potato slices at different ratios. The results revealed a remarkable suppressing effect on E. carotovora infection. The active component was further analyzed using different cell fractions, and the cell surface-projected fusion protein was found to correspond to the suppressing effect.