Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States.
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
ACS Appl Mater Interfaces. 2020 Jul 1;12(26):29056-29065. doi: 10.1021/acsami.0c05792. Epub 2020 Jun 17.
We report aqueous emulsions of thermotropic liquid crystals (LCs) that can intercept and report on the presence of -acyl-l-homoserine lactones (AHLs), a class of amphiphiles used by pathogenic bacteria to regulate quorum sensing (QS), monitor population densities, and initiate group activities, including biofilm formation and virulence factor production. The concentration of AHL required to promote "bipolar" to "radial" transitions in micrometer-scale droplets of the nematic LC 4'-pentyl-cyanobiphenyl (5CB) decreases with increasing carbon number in the acyl tail, reaching a threshold concentration of 7.1 μM for 3-oxo-C12-AHL, a native QS signal in the pathogen . The LC droplets in these emulsions also respond to biologically relevant concentrations of the biosurfactant rhamnolipid, a virulence factor produced by communities of under the control of QS. Systematic studies using bacterial mutants support the conclusion that these emulsions respond selectively to the production of rhamnolipid and AHLs and not to other products produced by bacteria at lower (subquorate) population densities. Finally, these emulsions remain configurationally stable in growth media, enabling them to be deployed either in bacterial supernatants or in bacterial cultures to eavesdrop on QS and report on changes in bacterial group behavior that can be detected in real time using polarized light. Our results provide new tools to detect and report on bacterial QS and virulence and a materials platform for the rapid and monitoring of bacterial communication and resulting group behaviors in bacterial communities.
我们报告了热致液晶（LC）的水包乳液，它可以拦截并报告酰基高丝氨酸内酯（AHL）的存在，酰基高丝氨酸内酯是一种用于调节群体感应（QS）、监测种群密度并启动群体活动（包括生物膜形成和毒力因子产生）的两亲性物质。在微米级棒状 LC 4'-戊基-氰基联苯（5CB）液滴中，AHL 浓度的增加可以促进“双极”到“径向”的转变，对于酰基尾部碳数增加的 3-氧代-C12-AHL，达到了 7.1 μM 的阈值浓度，3-氧代-C12-AHL 是病原体中天然的 QS 信号。这些乳液中的 LC 液滴也可以响应生物相关浓度的生物表面活性剂鼠李糖脂，鼠李糖脂是一种由 QS 控制的 社区产生的毒力因子。使用细菌突变体的系统研究支持了这样的结论，即这些乳液选择性地响应鼠李糖脂和 AHL 的产生，而不是响应细菌在较低（亚群体）种群密度下产生的其他产物。最后，这些乳液在生长介质中保持构型稳定，使它们可以部署在细菌上清液或 中，以便在 QS 上窃听并报告细菌群体行为的变化，这些变化可以使用偏振光实时检测。我们的结果提供了新的工具来检测和报告细菌的 QS 和毒力，并为快速和 监测细菌群落中的细菌通信和由此产生的群体行为提供了材料平台。
