Isolation, identification and regulation of quorum sensing signal molecules of Acinetobacter in Litopenaeus vannamei

Abstract:

[Objective] We detected and analyzed N-acyl-homoserine lactones (AHLs) of Acinetobacter spp. (M1) that was isolated from spoilage Litopenaeus vannamei. We also investigated the effects of bacteria growth stages and environmental factors on activities of signaling molecules. [Methods] The reporter strains (Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136) and TLC (Thin-Layer Chromatography) method were used to detect and analyze AHLs activities of M1. [Results] AHLs secreted by M1 were N-3-oxo-C6-HSL and N-3-x-oxo-C8-HSL. The activities of AHLs increased first and then decreased with the prolongation of the culture time under appropriate culture conditions, and reached the maximum in late logarithmic stage. The ability of M1 producing AHLs was reduced by weak acid and alkalescent envirornment, the optimum pH of M1 secreting AHLs was pH 7.0. The concentration of NaCl had no significant effect on the whole ability of M1 secreting AHLs, while high concentration promoted the ability of individual to product AHLs. The optimal temperature for strain M1 to produce AHLs was 30 °C, and the relative higher or lower temperature inhibited the AHLs secretion. [Conclusion] The AHLs of strain M1 were N-3-oxo-C6-HSL and N-3-oxo-C8-HSL. Quorum sensing systems of M1 was regulated by both cell density and environmental factors.

Key words:Acinetobacter spp., Quorum sensing, N-Acyl-homoserine lactones