The Racah Institute of Physics, The Hebrew University, Jerusalem, Israel.
Commun Biol. 2024 Aug 21;7(1):1028. doi: 10.1038/s42003-024-06698-1.
Chemotaxis-the movement of cells along chemical gradients-leads to collective behaviors when cells coordinate their movements. Here, using Escherichia coli as a model, we demonstrate a distinct type of bacterial collective response in acidic environments containing organic acids. Bacterial populations immersed in such environments collectively condensed into millimeter-sized focal points. Furthermore, this bacterial condensation fostered the formation of small, tightly packed cell aggregates, resembling non-surface-attached biofilms. These cell aggregates were physically displaced by the free-swimming condensing cells, leading to the segregation of the two cell populations. Bacterial condensation relied on feedback between the tendency of these bacteria to neutralize the pH and their chemotactic repulsion from low pH. Sustained cell condensation occurred when the bacteria occupied only part of the acidic environment, either dynamically or due to physical constraints. Such condensed bacterial populations can mitigate acid stress more efficiently, a principle that may be applicable to other stress conditions.
趋化性——细胞沿着化学梯度的运动——导致细胞协调运动时的集体行为。在这里，我们使用大肠杆菌作为模型，在含有有机酸的酸性环境中展示了一种独特的细菌集体反应类型。浸泡在这种环境中的细菌种群集体凝聚成毫米大小的焦点。此外，这种细菌凝结促进了小而紧密的细胞聚集体的形成，类似于非表面附着的生物膜。这些细胞聚集体被自由游动的凝结细胞物理位移，导致两种细胞群体的分离。细菌凝结依赖于这些细菌中和 pH 值的趋势和它们对低 pH 值的趋化排斥之间的反馈。当细菌只占据酸性环境的一部分时，无论是动态的还是由于物理限制，持续的细胞凝结都会发生。这种浓缩的细菌群体可以更有效地减轻酸应激，这一原则可能适用于其他应激条件。
