Abstract：
Benzalkonium chloride (BAC) is a disinfectant with broad-spectrum antibacterial properties, yet despite its widespread use and detection in the environment, the effects of BAC exposure on microorganisms remain poorly documented. Herein, the impacts of BAC on a Pseudomonas aeruginosa strain Jade-X were systematically investigated. The results demonstrated that the minimum inhibitory concentration (MIC) of BAC against strain Jade-X was 64 mg L-1. Exposure to BAC concentrations of 8, 16, 32, and 64 mg L-1 significantly augmented biofilm formation by 2.03-, 2.43-, 2.96-, and 2.56-fold respectively. The swimming and twitching abilities, along with the virulence factor production, were inhibited. Consistently, quantitative reverse transcription PCR assays revealed significant downregulation of genes related to flagellate- and pili-mediated motilities (flgD, flgE, pilB, pilQ, and motB), as well as phzA and phzB genes involved in pyocyanin production. The results of disk diffusion and MIC assays demonstrated that BAC decreased the antibiotic susceptibility of ciprofloxacin, levofloxacin, norfloxacin, and tetracycline. Conversely, an opposite trend was observed for polymyxin B and ceftriaxone. Genomic analysis revealed that strain Jade-X harbored eleven resistance-nodulation-cell division efflux pumps, with mexCD-oprJ exhibiting significant upregulation while mexEF-oprN and mexGHI-opmD were downregulated. In addition, the quorum sensing-related regulators LasR and RhlR were also suppressed, implying that BAC might modulate the physiological and biochemical behaviors of strain Jade-X by attenuating the quorum sensing system. This study enhances our understanding of interactions between BAC and P. aeruginosa, providing valuable insights to guide the regulation and rational use of BAC.
摘要：
苯扎氯铵（BAC）是一种具有广谱抗菌特性的消毒剂，然而，尽管它在环境中被广泛使用和检测，BAC暴露对微生物的影响尚不清楚。在这里，系统研究了BAC对铜绿假单胞菌Jade-X的影响。结果表明，BAC对Jade-X菌株的最低抑菌浓度（MIC）为64mgL-1。暴露于浓度为8、16、32和64mgL-1的BAC可显著增强生物膜形成2.03-，2.43-，2.96-,和2.56倍分别。游泳和抽搐的能力，随着毒力因素的产生，被抑制。始终如一，定量逆转录PCR检测揭示了与鞭毛和菌毛介导的运动性相关的基因的显着下调（flgD，flgE,pilB,pilQ,和motB)，以及phzA和phzB基因参与绿脓苷的生产。圆盘扩散和MIC测定的结果表明，BAC降低了环丙沙星的抗生素敏感性，左氧氟沙星,诺氟沙星,还有四环素.相反，多粘菌素B和头孢曲松的趋势相反。基因组分析显示，Jade-X菌株具有11个抗性-结瘤-细胞分裂外排泵，mexCD-oprJ表现出显着上调，而mexEF-oprN和mexGHI-opmD下调。此外,与群体感应相关的调节器LasR和RhlR也被抑制，暗示BAC可能通过减弱群体感应系统来调节Jade-X菌株的生理生化行为。这项研究增强了我们对BAC和铜绿假单胞菌之间相互作用的理解，为指导BAC的规范和合理使用提供有价值的见解。
