Enzymatic degradation of quorum-sensing signals to decrease bacterial phytopathogenicity

Quorum sensing (QS) allows bacterial populations to coordinate gene expression in a cell density dependent manner and plays a significant role in the onset of pathogenesis and biofilm development. In many Gram-negative bacteria, QS is mediated by signaling molecules called N-acyl-homoserine lactones (AHLs). We recently identified an AHL acylase from P. syringae which can enzymatically degrade and inactivate the AHLs used by phytopathogens. Similarly, during the Phase I project, we discovered a new AHL acylase from a closely-related pseudomonad. Our technological innovation is the use of these AHL acylases to degrade the AHL signals of bacterial phytopathogens and reduce plant disease. Our research objectives for the Phase II project will be to continue to advance our technologies by evaluating their efficacy in field trials. We will increase the production scale of heterologous protein and then evaluate formulations of exogenous acylase. We will also further develop our biocontrol strains and plants that constitutively produce AHL acylases. QS is a nonessential cellular process and so, unlike existing antibiotics that target indispensible functions, the targeted degradation of QS signals will exert significantly reduced selective pressure on plant pathogens and slow resistance development. The enzymatic degradation of QS signals will be environmentally friendly and will be advantageous over existing disease management strategies.