Bacterial biofilms are major contributors to chronic infections in humans. Because they are recalcitrant to conventional therapy, they present a particularly difficult treatment challenge. Identifying factors involved in biofilm development can help uncover novel targets and guide the development of antibiofilm strategies. Pseudomonas aeruginosa causes surgical site, burn wound, and hospital-acquired infections and is also associated with aggressive biofilm formation in the lungs of cystic fibrosis patients. A potent but poorly understood contributor to P. aeruginosa virulence is the ability to produce outer membrane vesicles (OMVs). OMV trafficking has been associated with cell-cell communication, virulence factor delivery, and transfer of antibiotic resistance genes. Because OMVs have almost exclusively been studied using planktonic cultures, little is known about their biogenesis and function in biofilms. Several groups have shown that Pseudomonas quinolone signal (PQS) induces OMV formation in P. aeruginosa. Our group described a biophysical mechanism for this and recently showed it is operative in biofilms. Here, we demonstrate that PQS-induced OMV production is highly dynamic during biofilm development. Interestingly, PQS and OMV synthesis are significantly elevated during dispersion compared to attachment and maturation stages. PQS biosynthetic and receptor mutant biofilms were significantly impaired in their ability to disperse, but this phenotype was rescued by genetic complementation or exogenous addition of PQS. Finally, we show that purified OMVs can actively degrade extracellular protein, lipid, and DNA. We therefore propose that enhanced production of PQS-induced OMVs during biofilm dispersion facilitates cell escape by coordinating the controlled degradation of biofilm matrix components.

中文翻译：

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假单胞菌喹诺酮信号诱导的外膜囊泡增强铜绿假单胞菌中的生物膜分散

细菌生物膜是导致人类慢性感染的主要因素。因为它们对常规疗法顽固，所以它们提出了特别困难的治疗挑战。确定参与生物膜发展的因素可以帮助发现新的目标并指导抗生物膜策略的发展。铜绿假单胞菌引起手术部位、烧伤和医院获得性感染，并且还与囊性纤维化患者肺部的侵袭性生物膜形成有关。铜绿假单胞菌的一种有效但知之甚少的贡献者毒力是产生外膜囊泡 (OMV) 的能力。OMV 运输与细胞间通讯、毒力因子传递和抗生素抗性基因的转移有关。由于 OMV 几乎完全是使用浮游培养物进行研究的，因此对其在生物膜中的生物发生和功能知之甚少。几个小组已经表明，假单胞菌喹诺酮信号 (PQS) 在铜绿假单胞菌中诱导 OMV 形成. 我们的小组为此描述了一种生物物理机制，最近表明它在生物膜中有效。在这里，我们证明了 PQS 诱导的 OMV 生产在生物膜发展过程中是高度动态的。有趣的是，与附着和成熟阶段相比，PQS 和 OMV 合成在分散过程中显着提高。PQS 生物合成和受体突变生物膜的分散能力显着受损，但这种表型通过遗传互补或外源添加 PQS 得以挽救。最后，我们表明纯化的 OMV 可以主动降解细胞外蛋白质、脂质和 DNA。因此，我们建议在生物膜分散过程中增加 PQS 诱导的 OMV 的产生，通过协调生物膜基质成分的受控降解来促进细胞逃逸。