生物膜铜绿假单胞菌群体感应系统调控ampC基因表达的研究

Effect of Quorum Sensing Systems in Pseudomonas aeruginosa Biofilms on Expression of AmpC Gene

目的研究生物膜铜绿假单胞菌(PAE)在抗菌药物诱导状态下,群体感应(QS)系统对产酶基因ampC表达的影响。方法改良的平板法建立PAE生物膜模型,抗菌药物诱导ampC基因表达,实时荧光定量PCR测定PAO1、PAO1加用QS抑制剂(呋喃酮C-30)及QS系统突变菌株的ampC基因表达水平。结果PAO1加用呋喃酮C-30后,浮游菌和生物膜菌的ampC基因表达水平均下调,生物膜菌下调的程度大于浮游菌,两者差异有统计学意义(P<0.05);QS系统突变菌株PAO-MW1、PAO-JP1的ampC基因表达水平均较PAO1低,生物膜状态PAO-MW1与PAO1的ampC基因表达差异较浮游状态更大。结论生物膜PAE的QS系统直接或间接调控ampC基因的诱导表达,QS系统发挥调控作用的水平不同可能是生物膜菌较浮游菌易诱导产酶原因之一。

OBJECTIVE To study the effect of quorum sensing（QS） systems in Pseudomonas aeruginosa biofilms on the expression of ampC gene induced by antibiotics. METHODS An in vitro model of P. aeruginosa bacterial biofilms was established with modified flat-board method. Being induced by antibiotics, the expression of ampC gene in the PAO1, PAO1 with QS inhibitor（furanone C-30） and the mutants in QS systems was quantified by realtime quantitative PCR. RESULTS With the effect of furanone C-30, the expression of ampC gene in PAO1 induced by antibiotics at the planktonic and biofilm phase was down-regulated. Futhermore the down-regulation at the expression of ampC gene in biofilm PAO1 was larger than that in planktonic PAO1, the difference between the two phases of PAO1 was significant with statistic test method （P〈 0. 05）. Being induced by antibiotics at both planktonic and biofilm phases, the expression of ampC gene in PAO-MW1 and PAO-JP1 was lower than that in PAOl,the difference between PAO-MW1 and PAO1 at biofilm phase was larger than that in planktonic phase. CONCLUSIONS QS systems in P. aeruginosa biofilm can regulate the expression of ampC gene induced by antibiotics by direct or indirect way. One possible reason of P. aeruginosa biolfilm showing stronger ability for β-lactamase production induced by antibiotics than planktonic bacteria is the different regulating effect of QS system at two phases.