Integrated Bioscience, University of Akron, Akron, OH, USA.
J Theor Biol. 2012 Sep 7;308:68-78. doi: 10.1016/j.jtbi.2012.05.029. Epub 2012 Jun 4.
We present a mathematical model of mushroom-like architecture and cavity formation in Pseudomonas aeruginosa biofilms. We demonstrate that a proposed disparity in internal friction between the stalk and cap extracellular polymeric substances (EPS) leads to spatial variation in volumetric expansion sufficient to produce the mushroom morphology. The capability of diffusible signals to induce the formation of a fluid-filled cavity within the cap is then investigated. We assume that conversion of bacteria to the planktonic state within the cap occurs in response to the accumulation or depletion of some signal molecule. We (a) show that neither simple nutrient starvation nor signal production by one or more subpopulations of bacteria is sufficient to trigger localized cavity formation. We then (b) demonstrate various hypothetical scenarios that could result in localized cavity formation. Finally, we (c) model iron availability as a detachment signal and show simulation results demonstrating cavity formation by iron starvation. We conclude that iron availability is a plausible mechanism by which fluid-filled cavities form in the cap region of mushroom-like structures.
我们提出了一个关于粘细菌生物膜中蕈状结构和腔形成的数学模型。我们证明，在柄部和帽部细胞外聚合物（EPS）之间存在内部摩擦力的差异，这导致了足够的体积膨胀的空间变化，从而产生蕈状形态。然后，我们研究了可扩散信号诱导帽部形成充满液体的腔的能力。我们假设，在帽部，细菌向浮游状态的转换是对某种信号分子的积累或耗尽的反应。我们（a）表明，简单的营养饥饿或一个或多个细菌亚群产生信号都不足以引发局部腔的形成。然后，我们（b）展示了可能导致局部腔形成的各种假设情况。最后，我们（c）将铁的可用性建模为一种分离信号，并展示了通过铁饥饿形成腔的模拟结果。我们的结论是，铁的可用性是形成蕈状结构帽部充满液体的腔的一种合理机制。
