不同理化条件对粪肠球菌生长周期及生物膜形成能力的影响

Effect of different stress conditions on growth and biofilm formation capability of Enterococcus faecalis

目的研究粪肠球菌在不同理化条件下生长周期和生物膜形成能力的变化。方法在体外不同次氯酸钠体积分数（1％、2％、5％）、不同葡萄糖质量分数（0、0．05％、0．15％）及不同pH值（9、10、11、12）条件下培养粪肠球菌，紫外分光光度计测定各种理化条件下粪肠球菌在96h内的A600值，观察粪肠球菌生长曲线的变化。在玻片上形成生物膜后分别采用活菌菌落计数和激光共聚焦显微镜观察测定粪肠球菌在各理化条件下生物膜的形成能力。结果在2％、5％NaClO及pH=11、12的条件下粪肠球菌不能生长，96h内的A600值均无增长。在1％NaCIO、pH=9、10及0、0．05％、0．15％葡萄糖条件下粪肠球菌的生长速度和生长量均有不同程度的下降：在1％NaClO条件下10h后A600值开始增长，16h时A600值达1．461（对照组6h A600值达峰值1．238）；0、0．05％、0．15％葡萄糖条件下，在6h时A600值均达峰值分别为0．645、0．890、1．173（对照组6h A600值最大为1．195）；在pH=9的条件下，6h时A600值达峰值为1．704，在pH=10条件下，10h时A600值才达峰值1．255（pH=7的条件下6h达峰值为1．732）。除5％NaClO和pH=12以外其他条件下粪肠球菌均能形成生物膜。结论粪肠球菌在寡能量、低体积分数的次氯酸钠及弱碱性环境下均能生长并形成生物膜。

Objective To study the changes of growth and biofilm formation capability of Enterococcus faecalis （Ef） in different stress conditions. Methods The changes of growth of Ef in stress conditions were observed by measuring the A600 value with uhravioiet spectrophotometer. Ef was incubated on glass slide in stress conditions, biofilm formation capability of cells was investigated by colony-forming unit （CFU） counting of the culturable bacteria and fluorescence confocal laser scanning microscopy. Results Ef couldn＇t growth under the conditions of 2% ,5% NaClO, pH = 11 and 12, the A600 value was unchanged in 96 hours. But the growth curve changed at different levels in other stress conditions ： under 1% NaClO, the A600 value peaked at 1. 461 at 16 hour（the peaked level was 1. 238 at 6 hours in control group） ; under 0, 0. 05% ,0. 15% glucose, it peaked at 0. 645,0. 890, 1. 173, respectively, at 6 hour（ it was maximized to 1. 195 at 6 hours in control group） ;the A600 value peaked at 1. 704 at 6 hours at pH = 9 and 1. 225 at l0 hours at pH = 10（ the peak level was 1. 732 at 6 hours at pH = 7）. Biofilm assay showed that Ef were able to form biofllm in these stress conditions except 5% NaClO and pH = 12. Conclusions Ef could growth and form biofilms in energy starvation,low concentrations of sodium hypochlorite and weak alkaline stress.