铜绿假单胞菌群体感应系统调控生物膜形成与AmpC基因表达的研究

Quorum sensing systems in pseudomonas aeruginosa in regulating formation of biofilms and expression of AmpC gene

目的研究铜绿假单胞菌(PAE)标准菌株PAO-1与不同的群体感应(QS)系统缺陷菌株的生物膜形态和生物膜状态下产酶基因AmpC的表达差异。方法改良的平板法建立PAE生物膜模型,银染法鉴定生物膜生成,观察PAO-1和不同突变菌株形成生物膜的形态;抗菌药物诱导生物膜菌AmpC基因表达,采用实时荧光定量PCR方法测定PAO1、QS系统缺陷菌株的AmpC基因表达水平。结果 PAO-1和突变菌株PDO100形成的生物膜较厚、层次多、致密,而突变菌株PAO-JP1和PAO-MW1形成的生物膜较少,分布不均匀;在生物膜状态运用抗菌药物诱导,QS系统缺陷菌株PAO-MW1、PAO-JP1的AmpC基因表达水平均较PAO1和缺陷菌株PDO100低,差异有统计学意义(P<0.05)。结论 PAE生物膜形成和AmpC基因诱导表达可能与las QS系统发挥的直接或间接调控作用有关,而rhl QS系统较少或是未参与生物膜形成和AmpC基因表达调控。

OBJECTIVE To study the differences of the biofilm morphology and the expression of AmpC gene induced by antibiotics at biofilm phases in Pseudomonas aeruginosastandard strains PAO-1 and various kinds mutants in quorum sensing systems.METHODS The in vitro model of P.aeruginosabacterial biofilms was established in silicon disk with modified flat-board method.Biofilm generation was identified by silver staining and biofilm morphology was observed by optical microscope.At the state of being induced by antibiotics,the expression of AmpC gene in PAO1,the mutants in quorum sensing systems was quantified by real-time quantitative PCR.RESULTS The biofilm of PAO-1 and PDO100 was thicker and more dense than that of PAO-JP1 and PAO-MW1.Being induced by antibiotics at biofilm phases,the expression of AmpC gene in PAO-MW1 and PAO-JP1 was lower than that in PAO1 and PDO100,the difference was statistically method（P0.05）.CONCLUSION The las quorum sensing systems in P.aeruginosacan regulate the biofilm formation and the expression of AmpC gene induced by antibiotics by direct or indirect way,but the rhl quorum sensing systems is less or not involved in them.