Curk Tine, Marenduzzo Davide, Dobnikar Jure
Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.
PLoS One. 2013 Oct 3;8(10):e74878. doi: 10.1371/journal.pone.0074878. eCollection 2013.
We simulate the dynamics of a suspension of bacterial swimmers, which chemotactically sense gradients in either ambient or self-secreted attractants (e.g. nutrient or aspartate respectively), or in both. Unlike previous mean field models based on a set of continuum partial differential equations, our model resolves single swimmers and therefore incorporates stochasticity and effects due to fluctuations in the bacterial density field. The algorithm we use is simple enough that we can follow the evolution of colonies of up to over a million bacteria for timescales relevant to pattern formation for E. coli growing in semisolid medium such as agar, or in confined geometries. Our results confirm previous mean field results that the patterns observed experimentally can be reproduced with a model incorporating chemoattractant secretion, chemotaxis (towards gradients in the chemoattractant field), and bacterial reproduction. They also suggest that further experiments with bacterial strains chemotactically moving up both nutrient and secreted attractant field may yield yet more dynamical patterns.
我们模拟了细菌游动体悬浮液的动力学过程，这些细菌能够通过趋化作用感知环境中或自身分泌的引诱剂（例如分别为营养物质或天冬氨酸）的梯度，或者同时感知两者的梯度。与先前基于一组连续偏微分方程的平均场模型不同，我们的模型解析单个游动体，因此纳入了随机性以及细菌密度场波动所产生的影响。我们使用的算法足够简单，以至于在与诸如琼脂等半固体培养基中生长的大肠杆菌的模式形成相关的时间尺度上，我们能够跟踪多达一百万个以上细菌菌落的演化过程，或者在受限几何形状中进行跟踪。我们的结果证实了先前平均场的结果，即通过纳入化学引诱剂分泌、趋化作用（朝向化学引诱剂场中的梯度）和细菌繁殖的模型，可以重现实验中观察到的模式。这些结果还表明，使用能够在营养物质和分泌引诱剂场中都进行趋化运动的细菌菌株进行进一步实验，可能会产生更多的动态模式。
