rmlB基因在单核细胞增生李斯特菌耐药性、生物被膜形成和毒力方面的作用

Contribution of rmlB in envelope-acting antibiotic resistance, biofilm formation and virulence in Listeria monocytogenes

【目的】探究单核细胞增生李斯特菌(Listeria monocytogenes,Lm)rmlB基因在细菌耐药、生物被膜形成和毒力方面的作用。【方法】通过同源重组的方法敲除Lm染色体上的rmlB基因,比较野生株与rmlB缺失株在耐药性方面的差异;利用微孔板法观测rmlB缺失菌株生物被膜形成能力的变化;利用RT-PCR检测缺失菌株中主要毒力基因转录表达,并观察rmlB缺失对细菌溶血活性的影响。【结果】同野生菌株相比,rmlB缺失菌株对头孢菌素和杆菌肽等作用位点在细菌细胞壁和细胞膜的敏感性显著增加(P≤0.01),生物被膜形成能力显著降低(P≤0.01),细菌主要毒力基因hly的转录表达及溶血活性也发生显著降低(P≤0.01)。【结论】rmlB基因在Lm生物被膜形成和耐受作用位点位于细胞壁和细胞膜的抗生素及细菌毒力方面具有重要作用。

[Objective] To explore the function of rmlB gene on antibiotic resistance, biofilm formation, and virulence in Listeria monocytogenes. [Methods] The rmlB gene was deleted through homologous recombination. Antibiotic resistancedifferences between the wild-type and the rmlB deletion mutant were compared. The biofilm formation ability of the mutant was measured using the microtiter plate assay. The transcription of major virulence genes in L. monocytogenes and hemolytic activity of the mutant were studied. [Results] Compared tothe wild-type strain, the deletion of rmlB increased susceptibility to envelope-acting antibiotics such as several cephalosporinsand bacitracin（P≤0.01） and decreased bacterial biofilm formation（P≤0.01）.The transcription expression of the well-known virulencegene hly in L. monocytogenes and bacterial haemolytic activity were also significantly reduced in the rmlB deletion mutant（P≤0.01）. [Conclusion] rmlB plays a crucial role in L. monocytogenes against the envelope-acting antibiotics, biofilm formation and virulence.