eDNA-stimulated cell dispersion from Caulobacter crescentus biofilms upon oxygen limitation is dependent on a toxin-antitoxin system

In their natural environment, most bacteria preferentially live as complex surface-attached multicellular colonies called biofilms. Biofilms begin with a few cells adhering to a surface, where they multiply to form a mature colony. When conditions deteriorate, cells can leave the biofilm. This dispersion is thought to be an important process that modifies the overall biofilm architecture and that promotes colonization of new environments. In Caulobacter crescentus biofilms, extracellular DNA (eDNA) is released upon cell death and prevents newborn cells from joining the established biofilm. Thus, eDNA promotes the dispersal of newborn cells and the subsequent colonization of new environments. These observations suggest that eDNA is a cue for sensing detrimental environmental conditions in the biofilm. Here we show that the toxin-antitoxin system (TAS) ParDE4 stimulates cell death in areas of a biofilm with decreased O2 availability. In conditions where O2 availability is low, eDNA concen...

在自然环境中，大多数细菌倾向于以复杂的表面附着多细胞集落形式生存，这类集落被称为生物被膜（biofilm）。生物被膜的形成始于少量细胞附着于表面，随后这些细胞增殖形成成熟集落。当环境条件恶化时，细胞可脱离生物被膜。这种播散过程被认为是改变生物被膜整体结构、并促进新环境定植的重要过程。
在新月柄杆菌（Caulobacter crescentus）的生物被膜中，胞外DNA（eDNA）会在细胞死亡时被释放，并阻止新生细胞加入已形成的生物被膜。
因此，胞外DNA可促进新生细胞的解离以及后续对新环境的定植。上述观察结果表明，胞外DNA是感知生物被膜内不利环境条件的信号分子。
本研究表明，毒素-抗毒素系统（TAS）ParDE4会在氧气可用性降低的生物被膜区域中促进细胞死亡。在氧气可用性较低的条件下，胞外DNA浓度……