Role of gallic and p-coumaric acids in the AHL-dependent expression of flgA gene and in the process of biofilm formation in food-associated Pseudomonas fluorescens KM120

BACKGROUND In the process of Pseudomonas fluorescens biofilm formation, N-acyl-l-homoserine lactone (AHL)-mediated flagella synthesis plays a key role. Inhibition of AHL production may attenuate P. fluorescens biofilm on solid surfaces. This work validated the anti-biofilm properties of p-coumaric and gallic acids via the ability of phenolics to suppress AHL synthesis in P. fluorescens KM120. The dependence between synthesis of AHL molecules, expression of flagella gene (flgA) and the ability of biofilm formation by P. fluorescens KM120 on a stainless steel surface (type 304L) was also investigated. RESULTS Research was carried out in a purpose-built flow cell device. Limitations on AHL synthesis in P. fluorescens KM120 were observed at concentrations of 120 and 240 µmol L−1 of phenolic acids in medium. At such levels of gallic and p-coumaric acids the ability of P. fluorescens KM120 to synthesize 3-oxo-C6-homoserine lactone (HSL) was not observed. These concentrations caused decreased expression of flgA gene in P. fluorescens KM120. The changes in expression of AHL-dependent flgA gene significantly decreased the rate of microorganism colonization on the stainless steel surface. CONCLUSION Phenolic acids are able to inhibit biofilm formation. The results obtained in the work may help to develop alternative techniques for anti-biofilm treatment in the food industry. © 2015 Society of Chemical Industry