Characterisation of Quorum Sensing System and Its Role in Global Regulation in Hafnia alvei

Quorum sensing (QS) is a regulatory process achieved via cell-to-cell communication that involves release and detection of autoinducers (AIs), and which occurs in a wide range of bacteria. To date, QS has been associated with events of pathogenesis, biofilm formation, and antibiotic resistance in clinical, industrial, and agricultural contexts. The main objective of this study was to characterise the role of N-Acyl homoserine lactone (AHL) type QS in Hafnia alvei FB1, a bacterial strain isolated from frozen vacuum-packed fish paste meatballs, via identification of QS core genes using a genomic approach, followed by comparative transcriptomic profiling between QS-deficient mutants and wild-type strains. H. alvei FB1 is known to produce two types of AHLs, namely, N-(3-oxohexanoyl) homoserine lactone (3OC6-HSL) and N-(3-oxooctanoyl) homoserine lactone (3OC8-HSL). The complete genome sequence of strain FB1 was obtained and a single gene for AHL synthase (halI) and its cognate receptor (halR) were identified. QS-deficient mutants of FB1 were constructed via the {lambda}-Red recombineering method. Removal of the QS genes in strain FB1 affected mainly mechanisms in cell division and nutrient uptake, as well as resistance to a number of antibiotics, which are crucial for survival, adaptation and colonisation of both food and the host gut environment.