Quorum Quenching Enzyme (PF-1240) Capable to Degrade AHLs as a Candidate for Inhibiting Quorum Sensing in Food Spoilage Bacterium <i>Hafnia alvei</i>

Abstract

Quorum sensing (QS) is widely present in microorganisms in marine aquatic products. Owing to the use of antibiotics, many spoilage bacteria in aquatic products are drug resistant. In order to slow down this evolutionary trend, the inhibition of spoilage phenotype of spoilage bacteria by interfering with QS has become a research hot spot in recent years. In this study, we found a new QS quenching enzyme, PF-1240; it was cloned and expressed in Pseudomonas fluorescens 08. Sequence alignment showed that its similarity with N-homoserine lactone (AHL) acylase QuiP protein of Pseudomonas fluorescens (Pf 0-1) was 78.4%. SDS-PAGE confirmed that the protein is a dimer composed of two subunits, which is similar to the structure of AHL acylases. The concentration of heterologous expression in Escherichia coli (DE3) was 26.64 μg/mL. Unlike most AHL acylases, PF-1240 can quench AHLs with different carbon chain lengths and inhibit the quorum sensing of the aquatic spoilage bacterium Hafnia alvei. It can significantly reduce the formation rate of biofilm of H. alvei to 44.4% and the yield of siderophores to 54%, inhibit the production of protease and lipase, and interfere with the motility of H. alvei. Through these corruption phenotypes, the specific application effect of PF-1240 can be further determined to provide a theoretical basis for its application in the preservation of practical aquatic products.

Keywords

• quorum sensing quenching enzyme
• <i>Hafnia alvei</i>
• biofilm
• extracellular protease
• motility