Involvement of LuxS in Aeromonas salmonicida metabolism, virulence and infection in Atlantic salmon (Salmo salar L)

Quorum sensing is a bacterial density dependent communication system, which regarded to regulate cooperative behaviors of community and mediated by extracellular signal molecules named autoinducers (Al). Among various signals, autoinducer-2 (AI-2) is believed to be the messengers inter species and produced by LuxS. For Aeromonas salmonicida (A. salmonicida), an opportunistic pathogen to many cold-water teleost, little information has been known about the function of AI-2 and LuxS. Therefore, our aim was to preliminarily clarify the function of LuxS in A. salmonicida. The consequences demonstrated that wild type A. salmonicida exhibited Al-2 activity and luxS defective mutant strain fail to produce Al-2 signals. Furthermore, it was suggested that luxS deficiency could impact bacterial morphology, surface properties and virulence dramatically. Challenge experiment showed a tendency that immune factors expressed earlier when Atlantic salmon was infected with AluxS strain. Overall, we hypothesis that Al-2 quorum sensing could regulate the expression of A-layer protein coding gene vapA, and then influence bacterial survival ability when suffered from attack of the host immune system. Though additional studies are warranted, our study will supply a new thinking to control the damage caused by A. salmonicida. (C) 2017 Elsevier Ltd. All rights reserved.