Department of Mechanical Engineering, University of Vermont, Burlington, VT, 05405, USA.
Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, 05405, USA.
Bull Math Biol. 2020 Feb 1;82(2):27. doi: 10.1007/s11538-020-00701-6.
Bacterial biofilms play a critical role in environmental processes, water treatment, human health, and food processing. They exhibit highly complex dynamics due to the interactions between the bacteria and the extracellular polymeric substance (EPS), water, and nutrients and minerals that make up the biofilm. We present a hybrid computational model in which the dynamics of discrete bacterial cells are simulated within a multiphase continuum, consisting of EPS and water as separate interacting phases, through which nutrients and minerals diffuse. Bacterial cells in our model consume water and nutrients in order to grow, divide, and produce EPS. Consequently, EPS flows outward from the bacterial colony, while water flows inward. The model predicts bacterial colony formation as a treelike structure. The distribution of bacterial growth and EPS production is found to be sensitive to the pore spacing between bacteria and the consumption of nutrients within the bacterial colony. Forces that are sometimes neglected in biofilm simulations, such as lubrication force between nearby bacterial cells and osmotic (swelling) pressure force resulting from gradients in EPS concentration, are observed to have an important effect on biofilm growth via their influence on bacteria pore spacing and associated water/nutrient percolation into the bacterial colony.
细菌生物膜在环境过程、水处理、人类健康和食品加工中起着至关重要的作用。由于细菌与胞外聚合物（EPS）、水以及构成生物膜的营养物质和矿物质之间的相互作用，它们表现出高度复杂的动态特性。我们提出了一种混合计算模型，其中离散细菌细胞的动力学在多相连续体中进行模拟，该连续体由 EPS 和水作为单独的相互作用相组成，营养物质和矿物质通过这些相扩散。在我们的模型中，细菌细胞消耗水和营养物质来生长、分裂和产生 EPS。因此，EPS 从细菌菌落向外流动，而水向内流动。该模型预测细菌菌落的形成是树状结构。发现细菌生长和 EPS 产生的分布对细菌之间的孔隙间距和细菌菌落内营养物质的消耗敏感。在生物膜模拟中经常被忽略的力，例如附近细菌细胞之间的润滑力和 EPS 浓度梯度引起的渗透压（膨胀）力，通过影响细菌孔隙间距和相关的水/营养物质渗透到细菌菌落中，对生物膜生长有重要影响。
