Use of a microfluidic platform to uncover basic features of energy and environmental stress responses in individual cells of Bacillus subtilis

Bacteria use a variety of stress-sensing systems to sense and respond to diverse stressors and to ensure their survival under adverse conditions. The gram-positive bacterium Bacillus subtilis responds to energy stress (ATP depletion) and to environmental stressors using two distinct stress-sensing pathways that converge on the alternative sigma factor σB to provoke a general stress response. Past efforts to study the σB stress response in bulk culture and on agarose pads were unable to visualize the responses of individual cells under tightly controlled conditions for extended periods of time. Here we use a microfluidics-based strategy to discern the basic features of σB activation in single cells in response to energy and environmental stress, both immediately upon stressor exposure and for tens of generations thereafter. Upon energy stress at various levels of stressor, cells exhibited fast, transient, and amplitude-modulated responses but not frequency modulation as previously report...

细菌借助多种应激感应系统感知并响应各类应激源，以确保在不良环境中存活。革兰氏阳性菌（Gram-positive bacterium）枯草芽孢杆菌（Bacillus subtilis）可通过两条独立的应激感应通路，分别响应能量应激（ATP耗竭）与环境应激源，两条通路最终汇聚于替代σ因子σB（Alternative sigma factor σB），从而触发通用应激反应。过往针对批量培养体系及琼脂糖贴片上σB应激反应的研究，均无法在严格可控的条件下，长时间观测单个细胞的应激响应过程。本研究采用基于微流控的实验策略，解析了单细胞在遭遇能量与环境应激时σB激活的核心特征，既覆盖应激暴露即刻的响应，也涵盖后续数十代增殖周期内的动态变化。在不同强度的能量应激条件下，细胞呈现出快速、瞬时且受振幅调控的响应模式，而非此前研究所报道的频率调制模式……