The project aims at establishing an interspecies quorum sensing system in which Lactobacillus plantarum/Lactobacillus sakei can sense and reduce the virulence of Staphylococcus aureus. Many strains of S. aureus are the causative agents of gastroenteritis and are also responsible for the toxic shock syndrome. On the other hand, both L. plantarum and L. sakei are regarded as non-pathogenic mutualistic normal microbes. In this project, we hope to genetically engineer a Lactobacillus strain that can detect the presence of autoinducing peptide (AIP) released by S. aureus and thereby synthesize and secrete RNAIII inhibiting peptide (RIP) to the extracellular environment. This heptapeptide RIP with proven effectiveness to attenuate virulence of S. aureus can then block the pathogenecity of S. aureus infection.

Such interspecies quorum quenching system should be viewed as blocking agent of S. aureus pathogenicity.  Since quorum sensing (QS) is a natural species-specific self regulating mechanism that does not involve in bacterial growth, neither does it incur any bacteriocidal impact, inhibition of QS should not yield a strong selective pressure for development of resistance. Attenuation of S. aureus virulence by quorum-sensing inhibitors, rather than bactericidal or bacteriostatic drugs, is therefore a highly attractive concept for preventive medicine particularly when many antibiotics are usually ineffective at S. aureus.