腐败大菱鲆源格氏沙雷菌SG-05的分离鉴定及环境因素对其AHLs的调控

Identification of Serratia grimesii SG-05 Isolated from Spoilage Scophthalmus maximus and Regulation of AHLs

从腐败的大菱鲆中分离得到1株具有群体感应现象的菌株,根据生理生化鉴定及16S r RNA鉴定结果:该菌为格氏沙雷菌,命名为格氏沙雷菌SG-05。采用微生物传感菌琼脂扩散法检测菌株SG-05群体感应,探究其生长阶段N-酰基高丝氨酸内酯(AHLs)分泌规律及环境因素(碳源、pH)对其分泌AHLs的影响。研究表明,菌株SG-05能够诱导紫色杆菌CV026和根瘤农杆菌A136产生明显的颜色反应。随着培养时间的延长,菌株SG-05培养液pH逐渐升高,AHLs分泌量表现出先升高后降低的趋势,呈密度依赖性;在不同碳源(葡萄糖、果糖、木糖、麦芽糖等)培养基中生长,均促进菌株SG-05分泌AHLs,以果糖为碳源时AHLs分泌量最大;同时发现弱酸或中性环境适合菌株SG-05分泌AHLs,其中pH 6.0时AHLs分泌量达到最大值。研究证实细菌的菌液密度和外界环境因素能有效调控格氏沙雷菌AHLs的分泌。

A strain producing quorum sensing signals was isolated from spoilage Scophthalmus maximus. The strain was confirmed into Serratia grimesii according to its physiological-biochemical characteristics and 16 S r RNA gene analysis.AHLs were analyzed by the agar diffusion method using Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136. The effects of bacteria growth stages and the strain producing AHLs at different culture conditions were also investigated. The results showed that the strain could activate Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136, respectively. With the extension of culture time, the activities of AHLs increased in the initial period and then decreased in a concentration-dependent manner. The secretion of AHLs was promoted when they were grown in the different carbon sources（glucose, fructose, xylose, maltose） and the optimal carbon source for strain SG-05 to produce AHLs was fructose. The ability of strain producing AHLs was suitable to weak acid and neutral environment, the optimum p H secreting AHLs was p H 6.0. The study showed that sensing signals was dramaticallly regulated by bacterial densities as well as outer environmental factors.