Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana.
Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana.
Biotechnol Bioeng. 2020 Nov;117(11):3486-3498. doi: 10.1002/bit.27491. Epub 2020 Jul 28.
Biofilms commonly develop in flowing aqueous environments, where the flow causes the biofilm to deform. Because biofilm deformation affects the flow regime, and because biofilms behave as complex heterogeneous viscoelastic materials, few models are able to predict biofilm deformation. In this study, a phase-field (PF) continuum model coupled with the Oldroyd-B constitutive equation was developed and used to simulate biofilm deformation. The accuracy of the model was evaluated using two types of biofilms: a synthetic biofilm, made from alginate mixed with bacterial cells, and a Pseudomonas aeruginosa biofilm. Shear rheometry was used to experimentally determine the mechanical parameters for each biofilm, used as inputs for the model. Biofilm deformation under fluid flow was monitored experimentally using optical coherence tomography. The comparison between the experimental and modeling geometries, for selected horizontal cross sections, after fluid-driven deformation was good. The relative errors ranged from 3.2 to 21.1% for the synthetic biofilm and from 9.1 to 11.1% for the P. aeruginosa biofilm. This is the first demonstration of the effectiveness of a viscoelastic PF biofilm model. This model provides an important tool for predicting biofilm viscoelastic deformation. It also can benefit the design and control of biofilms in engineering systems.
生物膜通常在流动的水相环境中形成，在这种环境中，流动会导致生物膜变形。由于生物膜变形会影响流态，并且生物膜表现为复杂的非均质粘弹性材料，因此很少有模型能够预测生物膜变形。在这项研究中，开发了一种相场（PF）连续体模型，并与 Oldroyd-B 本构方程耦合，用于模拟生物膜变形。使用两种类型的生物膜（由藻酸盐与细菌细胞混合制成的合成生物膜和铜绿假单胞菌生物膜）来评估模型的准确性。使用剪切流变仪实验确定了每个生物膜的力学参数，并将其用作模型的输入。使用光相干断层扫描术（OCT）实验监测生物膜在流体流动下的变形。对选定水平横截面在流体驱动变形后的实验和建模几何形状进行比较，结果良好。对于合成生物膜，相对误差范围为 3.2%至 21.1%，对于铜绿假单胞菌生物膜，相对误差范围为 9.1%至 11.1%。这是首次证明粘弹性 PF 生物膜模型有效性的研究。该模型为预测生物膜粘弹性变形提供了重要工具。它还可以为工程系统中的生物膜设计和控制带来益处。
