Verticalization of bacterial biofilms
Verticalization of bacterial biofilms
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DOI：
10.1038/s41567-018-0170-4
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发表时间：
2018-09-01
期刊：
影响因子：
19.6
通讯作者：
Wingreen, Ned S.
中科院分区：
文献类型：
--
作者：
Beroz, Farzan;Yan, Jing;Wingreen, Ned S.
生物膜是附着在表面上的细菌群落。最近，杆状细菌的生物膜在单细胞分辨率下被观察到，并显示出从无序的二维创始细胞层发展成具有垂直排列的核心的三维结构。在这里，我们阐明了物理机制的基础上，这种转变使用相结合的基于代理和连续建模。我们发现，垂直化收益通过一系列的局部力学不稳定性的细胞尺度上。对于短细胞来说，这些不稳定性主要是由细胞分裂引发的，而长细胞更有可能被附近的垂直细胞从表面剥离，从而产生“反向多米诺骨牌效应”。细胞生长和细胞垂直化之间的相互作用产生了一种奇异的机械状态，其中有效表面压力在整个生物膜表面层的生长核心中变得恒定。这种动态等压性决定了生物膜簇的扩张速度，从而决定了细胞如何进入第三维空间。特别是，理论预测，较长的平均细胞长度产生更迅速扩张，更平坦的生物膜。我们的实验表明，这种变化在生物膜的发展发生利用化学物质，调节细胞长度。
Biofilms are communities of bacteria adhered to surfaces. Recently, biofilms of rod-shaped bacteria were observed at single-cell resolution and shown to develop from a disordered, two-dimensional layer of founder cells into a three-dimensional structure with a vertically aligned core. Here, we elucidate the physical mechanism underpinning this transition using a combination of agent-based and continuum modelling. We find that verticalization proceeds through a series of localized mechanical instabilities on the cellular scale. For short cells, these instabilities are primarily triggered by cell division, whereas long cells are more likely to be peeled off the surface by nearby vertical cells, creating an 'inverse domino effect'. The interplay between cell growth and cell verticalization gives rise to an exotic mechanical state in which the effective surface pressure becomes constant throughout the growing core of the biofilm surface layer. This dynamical isobaricity determines the expansion speed of a biofilm cluster and thereby governs how cells access the third dimension. In particular, theory predicts that a longer average cell length yields more rapidly expanding, flatter biofilms. We experimentally show that such changes in biofilm development occur by exploiting chemicals that modulate cell length.