黄芪对铜绿假单胞菌毒力因子调控表达及菌体运动的影响

Effects of Astragalus mongholicus on expression of pseudomonas aeruginosa virulence factors and somatic motility

[目的]观察黄芪对铜绿假单胞菌相关毒力因子表达及菌体运动的影响,探讨黄芪对铜绿假单胞菌的作用机制。[方法]不同浓度黄芪与对数生长期铜绿假单胞菌共培养,弹性蛋白-刚果红降解实验检测细菌分泌的弹性蛋白酶活性,紫外分光光度法测定绿脓菌素分泌量,结晶紫染色法观察生物被膜形成量,在含黄芪琼脂平板中检测菌体集群运动与泳动能力。[结果]黄芪在终浓度25、12.5、6.25 g/L条件下对弹性蛋白酶、绿脓菌素表达有显著抑制,并能抑制生物被膜形成。在低于12.5 g/L时对细菌增殖无显著影响。细菌在12.5 g/L条件下泳动能力与集群运动均受到显著影响。[结论]黄芪对铜绿假单胞菌增殖和毒力因子表达的抑制程度不一致,提示黄芪抑菌可能通过多种途径发挥抑菌功能,并可能在低浓度下便对密度感应系统造成显著抑制。

[Objective] To investigate the effects of Astragalus mongholicus on virulence factor of pseudomonas aeruginosa （PA） virulence and somatic motility and explore its mechanism. [Methods] The elastase activity was assessed quantitatively by elastin-Congo red degradation; the secretion of pyocyanin was determined with ultraviolet spectrophotometry after co-culture of different concentration of Astragalus mongholicus and PA at heterogonous grow phase; the biofilm formation was detected by crystal violet staining. The assay of somatic swarming was conducted in petri dishes, containing Astragalus mongholicus. [Results] The expression of elastase and pyocyanin were obviously inhibited at the concentration of 25 g/L, 12.5g/L and 6.25 g/L of Astragalus mongholicus and the biofilm formation was also inhibited. No effect on bacterial hyperplasia was found under 12.5 g/L. But the swimming and swarming motility of bacteria were reduced at 12.5 g/L. [Conclusion] Astragalus mongholicus can inhibit the hyperplasia and virulence factor of PA at different levels, indicating that the inhibition is controlled by multiple mechanisms, and the quorum sensing system can regulate these factors at a lower concentration of cultivation.