Collective membrane potential dynamics in bacterial colonies

枯草芽孢杆菌的结构化群体通过电通信来协调它们的代谢。目前，尚不清楚其他细菌物种是否同步它们的电化学行为。我们发现，在淋病奈瑟氏菌形成的球形菌落内，细菌在中心高度极化，随后，超极化细胞的壳径向地向殖民地的外围移动。这种超极化之后是在殖民地中心的去极化。在这个建议中，我们的目的是发现触发超极化，集体传播超极化的机制，其关系到增长停滞和相关后果的人口健身。具体而言，我们将在殖民地中心的生长停滞与膜电位相关联。为此，我们将结合联合收割机我们最近建立的方法来表征生长速率与时空分辨率的工具，用于表征膜电位。然后，我们的目标是调查两个假定的触发超极化。我们将评估是否氧气或营养素的耗尽导致超极化。此外，我们将检验在殖民地中心机械压力的积累限制生长并引起超极化的假设。我们将通过调整殖民地中淋球菌之间的吸引力来改变压力。吸引力将通过基因修饰4型皮利来调整，并通过激光镊子来表征。最后，我们将解决的问题是否细胞间的通信是需要传播的超极化。为此，我们将研究超极化波在不同群体结构中的时空动力学。从长远来看，它将是重要的，以确定负责超极化的离子通道，并解决集体的膜电位变化的健身效果。

Structured populations of Bacillus subtilis coordinate their metabolism by electrical communication. Currently, it is unknown, whether other bacterial species synchronize their electrochemical behavior. We found that within spherical colonies formed by Neisseria gonorrhoeae, bacteria hyperpolarize at the center and subsequently, a shell of hyperpolarized cells travels radially towards the periphery of the colony. This hyperpolarization is followed by depolarization at the colony center. In this proposal, we aim at discovering triggers for hyperpolarization, the mechanism of collective propagation of hyperpolarization, and its relation to growth arrest and related consequences on population fitness. Specifically, we will correlate growth arrest at the colony center with membrane potential. To this end, we will combine our recently established method for characterizing the growth rate with spatio-temporal resolution with tools for characterizing the membrane potential. Then, we aim at investigating two putative triggers of hyperpolarization. We will assess whether depletion of oxygen or a nutrient causes hyperpolarization. Furthermore, we will test the hypothesis that build-up of mechanical pressure at the center of the colony limits growth and causes hyperpolarization. We will vary the pressure by tuning the attractive force between gonococci in the colony. Attractive forces will be tuned by genetically modifying type 4 pili and characterized by laser tweezers. Finally, we will address the question whether cell-to-cell communication is required for the propagation of hyperpolarization. To this end, we will investigate the spatio-temporal dynamics of the hyperpolarization wave in different colony structures. In the long term, it will be important to identify the ion channels responsible for hyperpolarization and to address the fitness effects of collective changes in membrane potential.