一株嗜水气单胞菌的分离鉴定和不同条件对其群体感应AHLs活性的影响

Isolation, Identification, Quorum Sensing, and AHL Activity of Aeromonas hydrophila under Different Conditions

摘要:

本研究从腐败的大菱鲆中分离得到一株具有群体感应(Quorum Sensing, QS)的细菌，通过生理生化试验、16S rRNA鉴定其为嗜水气单胞菌(Ah-11)，采用报告平板打孔法探究其生长阶段N-酰基高丝氨酸内酯(AHLs)活性变化以及环境因素对其分泌的AHLs活性的影响。结果显示，菌株Ah-11能够诱导报告菌株紫色杆菌CV026和根癌农杆菌A136产生颜色反应；菌株Ah-11在生长阶段的AHLs活性随着培养时间的增加呈现先升高后降低趋势；不同碳源的液体培养基对Ah-11分泌AHLs的影响能力由高到低为麦芽糖>葡萄糖>蔗糖>果糖>乳糖>木糖；Ah-11在弱酸或者强碱条件下AHLs活性较低，pH=8.0时AHLs活性最大；较高浓度的氯化钠不仅会抑制Ah-11的生长，同时也抑制其AHLs的分泌，0.5~1.0 g/100 g的氯化钠质量浓度可以增强Ah-11的AHLs活性；菌株Ah-11分泌AHLs的最适温度为28 ℃，高温和低温都会影响其AHLs的分泌。研究证实细菌的群体密度和外界环境因素能够调控嗜水气单胞菌AHLs的分泌。

Abstract:

One quorum sensing (QS) strain was isolated from spoilage bacteria of Scophthalmus maximus and by using classical tests and 16S rRNA gene analysis, it was determined to be Aeromonas hydrophila. The changes in the activity of N-acyl-homoserine lactones (AHLs) during the growth stages of the strain and the effect of different culture conditions on the secretion of AHLs were studied by the punch method. The results indicated that the strain Ah-11 could induce Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136 to produce color. The activities of AHLs increased first and then decreased during the growth phase. The different carbon sources influenced the activity of AHLs in the following order: maltose> glucose> sucrose> fructose> lactose> xylose. The ability of Ah-11 to produce AHLs was reduced in weak acid and alkalescent environment; the optimum pH fat which Ah-11 could secrete AHLs was pH 8.0. Higher concentrations of NaCl would not only inhibit the growth of Ah-11 but also inhibit the activity of AHLs. The concentration of NaCl (0.5–1.0 g/100g) had a significant effect on the ability of Ah-11 to secrete AHLs. The optimal temperature at which the Ah-11 strain could produce AHLs was 28°C and relatively higher or lower temperatures could inhibit AHL secretion. Quorum sensing systems of Ah-11 were regulated by both the density of the bacteria and by environmental factors.