Modeling Biofilms: Fluid Dynamics, Reactions, Diffusion/Advection and Biomass Redistribution

生物膜建模：流体动力学、反应、扩散/平流和生物质再分配

• 批准号: 0548511
• 负责人: Nicholas Cogan
• 金额: $ 3.46万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0548511&HistoricalAwards=false
• 关键词: Modeling; Biofilms; Fluid; Dynamics; Reactions

This research is dedicated to the development and simulation of a new model of biofilm dynamics. Specifically, the model includes comprehensive fluid dynamics for a fluid flowing over a generic biofilm domain. The major advance in this model is to allow for the motion of the biofilm due to the fluid motion and growth processes. The biofilm is composed of multiple species of bacteria that consume multiple types of nutrients and produce both bacteria and exo-polymeric substance (EPS). The EPS is responsible for the redistribution of the biomass by virtue of the osmotic pressure that typifies hydrogels. By producing EPS in regions of higher nutrient concentration, gradients of EPS concentration are set up. These gradients induce a force on the biofilm tending to equilibrate the concentration of EPS. This physical description of biomass redistribution coupled with realistic motion of the biofilm due to growth is a substantial improvement over existing models. Much of the focus of the early investigations will concern numerical methods to incorporate the free boundary that marks the permanent separation between the bulk fluid and the biofilm regions. The methods that we are using are based on boundary integral methods that have been used successfully to model two fluid systems with various types of boundaries (e.g. elastic, passive). To use these methods, a generalized reciprocal theorem will be derived which includes the growth of the biofilm in the constitutive relationship. Once the reciprocal theorem is established, an integral equation can be derived that determines the velocity of the fluid/biofilm system.Microbial biofilms have a significant impact on virtually all areas of our lives. While these impacts can be beneficial, such as the use of biofilms in bioremediation and wastewater treatment, the majority of current research focuses on the detrimental processes associated with biofilm contamination. Negative impacts of biofilms include examples from such diverse areas as food service industries, chemical manufacturing plants, paper production plants and various medical settings. These impacts include increased cost, lowered efficiency, increased corrosion, fouling and increased impurities and infections. Realistic models of biofilm growth and development will aid experimentalists in proposing new experimental inquiries. Also, because detailed spatial data can be generated from model simulations more readily than by experimentation, novel hypotheses of persistent formation and detachment can be proposed based on values of concentrations and internal stresses.

本研究致力于开发和模拟一种新的生物膜动力学模型。具体而言，该模型包括流体在一般生物膜域上流动的综合流体动力学。该模型的主要进步是允许生物膜由于流体运动和生长过程而运动。生物膜由多种细菌组成，这些细菌消耗多种类型的营养物质并产生细菌和外聚合物质（EPS）。EPS是负责生物量的再分配凭借渗透压，典型的水凝胶。通过在养分浓度较高的地区生产EPS，建立了EPS浓度梯度。这些梯度在生物膜上产生一种力，趋于平衡EPS的浓度。这种生物质再分配的物理描述加上由于生长而产生的生物膜的真实运动是对现有模型的实质性改进。早期研究的大部分重点将放在数值方法上，以纳入自由边界，这标志着大块流体和生物膜区域之间的永久分离。我们使用的方法是基于边界积分方法，该方法已经成功地用于模拟具有不同类型边界（例如弹性，被动）的两种流体系统。为了使用这些方法，将推导出一个广义的互易定理，其中包括生物膜在本构关系中的生长。一旦建立了互易定理，就可以推导出确定流体/生物膜系统速度的积分方程。微生物生物膜对我们生活的几乎所有领域都有重大影响。虽然这些影响可能是有益的，例如在生物修复和废水处理中使用生物膜，但目前大多数研究都集中在与生物膜污染相关的有害过程上。生物膜的负面影响包括食品服务行业、化学制造工厂、造纸工厂和各种医疗环境等不同领域的例子。这些影响包括成本增加、效率降低、腐蚀加剧、结垢、杂质和感染增加。生物膜生长和发育的现实模型将有助于实验学家提出新的实验问题。此外，由于模型模拟比实验更容易产生详细的空间数据，因此可以根据浓度和内应力值提出关于持续形成和分离的新假设。