环境因素对即食海参蜂房哈夫尼菌群体感应的影响

Influence of Environmental Factors on Quorum Sensing of Hafnia alvei Isolated from Ready-to-eat Sea Cucumber

本文探究了即食海参腐败菌蜂房哈夫尼菌(Hafnia alvei H4)生长阶段N-酰基高丝氨酸内酯(AHLs)的分泌规律及环境因素对AHLs分泌的影响。以紫色杆菌CV026为报告菌,采用报告菌平板法检测H4分泌AHLs含量;以根癌农杆菌KYC55为报告菌,采用β-半乳糖苷酶法检测AHLs的活性。研究表明菌株H4分泌的AHLs含量及其活性具有密度依赖性,在细菌对数生长后期(OD600≈1.6)AHLs的分泌量达到最高,此时培养液的pH为5.71。环境因素对AHLs分泌影响的结果显示,在一定浓度范围内,添加Na Cl对H4分泌AHLs有促进作用;弱酸和弱碱都能使AHLs的分泌能力降低,pH为7.0时AHLs分泌量最大;H4分泌AHLs的最适温度为30℃,低温下AHLs分泌能力较弱。经不同碳源或氮源培养时,H4分泌AHLs的能力有明显差异,以果糖为碳源时,AHLs的活性最高,以硫酸铵为氮源时,AHLs的活性最高。综上所述,蜂房哈夫尼菌的群体感应系统具有密度依赖性,并且受环境因素影响,呈现规律性变化。

This study aimed to investigate the regularity of N-acyl homoserine lactone（AHL） secretion by spoilage bacteria Hafnia alvei H4 isolated from ready-to-eat sea cucumber, and the influence of environmental factors on AHL secretion. AHL content secreted by H4 were determined using Chromobacterium violaceum CV026, and AHL activity was detected by Agrobacterium tumefaciens KYC55 in a β-galactosidase assay. The results showed that the content and activities of AHLs secreted by H4 were density-dependent. AHL activity initially increased, and then decreased with time under appropriate culture conditions, reaching a maximum in the late logarithmic phase（OD600 ≈1.6; pH ≈5.71）. Testing for the influence of environmental factors on AHL secretion revealed that an increased concentration of sodium chloride promoted the secretion of AHLs by H4 within a certain concentration range. Secretion of AHLs was reduced under weakly acidic and alkaline environments, and AHL content was the highest when the environmental pH was 7.0. The optimum temperature for AHL secretion by H4 was found to be 30°C, and the ability of H4 to secrete AHLs was reduced at low temperatures. The ability of H4 to secrete AHLs was significantly different upon usage of different carbon or nitrogen sources; activities were the highest when fructose was used as the carbon source and ammonium sulfate as the nitrogen source. In conclusion, the quorum sensing system of Hafnia alvei H4 was density-dependent, influenced by environmental factors, and showed regular changes.