GOALI: Predicting Biofilm Deformation and Detachment Using In-Situ Micro-Rheology and Phase-Field Modeling

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1605177NerenbergIt is recognized in environmental technology and processes that bacterial biofilms play an important role. However, the understanding of how they are formed, their mechanical strength, and, in many cases, their contribution to actual changes which are observed in the environment, are poorly understood. To gain a better understanding of bacterial biofilms, this research will characterize the mechanical properties of biofilms, especially counter-diffusional biofilms relevant to the ZeeLung Membrane Aerated Biofilm Reactor from GE Power and Water, to allow prediction of biofilm deformation and detachment.Biofilm deformation and detachment remains a black box, where there are no reliable and mechanistic means to predict them. Also, few researchers have considered the viscoelastic behavior of biofilms. This research will determine the mechanical properties of heterotrophic, nitrifying, and combined heterotrophic and nitrifying biofilms, considering their viscoelastic behavior. It uses a unique, in-situ micro-scale technique to assess the spatial distribution of mechanical properties. In addition to studying pure-culture biofilms, this study will be the first to address the mechanical properties of a co-culture biofilm, where a known nitrifier and heterotrophs co-exist. The pure and co-culture results will be compared with an environmental biofilm at GE. The composition of the extracellular polymeric substance matrix will be determined in-situ and related to mechanical properties. The properties will be assessed as a function of time and shear stress, and also will assess the effect of an extracellular polymeric substance disruptor on mechanical properties. This is the first research to address the micro-scale spatial variability of biofilms relevant to environmental systems. It will also address a special type of tubular, sheath structure observed in heterotrophic, counter-diffusional biofilms, leading to dense, gelatinous biofilms. The research will develop novel information on the spatial and temporal variation of mechanical properties in biofilms under several environmentally relevant conditions, and will relate these properties to extracellular polymeric substance characteristics. It also will use a novel phase-field model to predict deformation and detachment, and the impact of spatial heterogeneity. The project will train one doctoral student, several undergraduate researchers and research experiences for undergraduate students, and partially support a post-doctoral researcher. It will provide an on-site experience at GE for a grad student or post-doc. Workshops between Notre Dame and GE will disseminate knowledge on biofilm research and process development at a global membrane process company, and promote local workforce development.