Department of Physics, Central University of Punjab, Bathinda 151401, India.
Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA.
Soft Matter. 2021 Oct 13;17(39):8858-8866. doi: 10.1039/d1sm00775k.
Bacterial biofilms cost an enormous amount of resources in the health, medical, and industrial sectors. To understand early biofilm formation, beginning from planktonic states of active suspensions (such as ) to micro-colonization, it is vital to study the mechanics of cell accumulation near surfaces and subsequent deposition. Variability in bacterial motion strategies and the presence of taxis fields make the problem even more multifaceted. In this study, analytical expressions for the density and angular distributions, mean orientation, and deposition rates in such bacterial suspensions are derived, with and without the effects of external guiding or taxis fields. The derived results are closely verified by simulations of confined active particles using run-and-tumble statistics from multiple past experiments and utilizing a preferential sticking probability model for deposition. The behavioral changes in cell running strategies are modeled by varying the run-time distribution from an exponential to a heavy-tailed one. It is found that the deposition rates can be altered significantly by a guiding torque but are less affected by a change in the cell running behavior. However, both the mechanisms alter the pair correlation function of the deposited structures. The factor behind the changes in the architecture of deposited biomass under a torque generating guiding field turns out to be an asymmetrical rotational drift of planktonic cells, which can be an important physical mechanism behind the organization in confined active particle suspensions.
细菌生物膜在医疗和工业领域造成了巨大的资源浪费。为了了解早期生物膜的形成，从浮游状态的活性悬浮液（如 ）开始到微定植，研究细胞在表面附近的积累和随后的沉积的力学特性是至关重要的。细菌运动策略的可变性和趋化场的存在使得问题更加复杂。在这项研究中，推导了在有和没有外部导向或趋化场影响的情况下，这种细菌悬浮液中的密度和角分布、平均取向和沉积速率的解析表达式。推导结果通过使用来自多个过去实验的运行和翻转统计数据并利用优先附着概率模型进行沉积的受限活性粒子的模拟得到了紧密验证。通过将运行时间分布从指数分布更改为重尾分布来模拟细胞运行策略的变化。结果发现，沉积速率可以通过导向扭矩显著改变，但受细胞运行行为变化的影响较小。然而，这两种机制都改变了沉积结构的对关联函数。在产生导向扭矩的场下，沉积生物质结构变化的原因是浮游细胞的不对称旋转漂移，这可能是受限活性粒子悬浮液中组织的重要物理机制。
