Heterologous Expression of the Marine-Derived Quorum Quenching Enzyme MomL Can Expand the Antibacterial Spectrum of .

Quorum sensing (QS) is closely associated with the production of multiple virulence factors in bacterial pathogens. -acyl homoserine lactones (AHLs) are important QS signal molecules that modulate the virulence of gram-negative pathogenic bacteria. Enzymatic degradation of AHLs to interrupt QS, termed quorum quenching (QQ), has been considered a novel strategy for reduction of pathogenicity and prevention of bacterial disease. However, the low expression levels of QQ proteins in the original host bacteria has affected the applications of these proteins. Previously, we identified a novel marine QQ enzyme, named MomL, with high activity and promising biocontrol function. In this study, we linked the target fragment to pNCMO2, which provided a basis for the first heterologous expression of MomL in the antifungal and anti-gram-positive-bacteria biocontrol strain , and obtaining the recombinant strain named MomL. The QQ activity of MomL was confirmed using a series of bioassays. MomL could not only degrade the exogenous signal molecule C6-HSL, but also the AHL signal molecules produced by the gram-negative pathogens subsp. () and PAO1. In addition, MomL significantly reduced the secretion of pathogenic factors and the pathogenicity of and PAO1. We tested the biocontrol function of MomL for prevention of plant diseases in vitro. The result indicates that MomL has a broad antibacterial spectrum. Compared with wild-type , MomL not only inhibited fungi and gram-positive bacterial pathogens but also considerably inhibited gram-negative bacterial pathogens. Moreover, the expression system has good application prospects and is an ideal host for expression and secretion of foreign proteins.