The effect of LuxR solo EvgA on the spoilage potential of Pseudomonas fluorescens

LuxR solos sense exogenous signaling molecules and regulate microbial behaviors, thus facilitating intra- and inter-species communication among bacteria. However, studies on the role of LuxR solos in regulating the spoilage potential of specific spoilage organisms are limited. In this study, we screened a LuxR solo EvgA, derived from Pseudomonas fluorescens PF08. qRT-PCR and molecular docking results indicated that EvgA responds and binds most strongly to exogenous N -3-tetradecanoyl-L-homoserine lactone (C14-HSL) through hydrogen bonds and hydrophobic interactions, with a –CDOCKER ENERGY of 45.87 kcal/mol. Subsequently, the evgA knockout (Δ evgA ) and complementary evgA (Δ evgA -com) mutants of P. fluorescens PF08 were constructed through homologous recombination. Δ evgA mutants displayed diminished eavesdropping to exogenous C14-HSL (by 18.99 ± 2.09%), reduced adhesion ability (by 30.33 ± 0.36%), attenuated biofilm formation (by 15.97 ± 0.14%), and decreased motility (swarming zones by 4.34 ± 0.002 mm and swimming zones by 4.17 ± 0.11 mm). In addition, EvgA deletion reduced spoilage factor production (hydrolysis zone), which included extracellular proteases, lipases, and biogenic amines (by 4.45 ± 0.51 mm, 10.12 ± 0.10 mm, and 14.41 ± 0.57 mm, respectively), thereby diminishing the spoilage of salmon fillets stored at 4 °C. Notably, the addition of exogenous C14-HSL promoted the spoilage ability of all strains. This study emphasizes the important role of LuxR solo EvgA in AHLs-mediated quorum sensing and the spoilage potential of P. fluorescens PF08, which is expected to be a new target for controlling the spoilage of aquatic products.