Microbial Flocculation Dynamics

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The investigator and his colleagues study the population dynamics of aqueous, multi-cellular, microbial communities. These communities are ubiquitous from the laboratory to the ocean, and the objective of this research is to advance understanding of microbial flocculation, the process whereby proliferating clusters of organisms in suspension fragment and aggregate. Specifically, the researchers use semigroup, fractal, partial differential equation, and computational analysis to advance the theory and applications for a novel class of structured population models. The close coupling between the model development, analysis, and experimental validation allows insight into the biomechanical and metabolic adaptations of this globally pervasive and fundamental state of microbial existence. The investigator and his colleagues are guided by three motivating questions: 1) what are the dominant mechanisms driving floc fragmentation? 2) How does floc structure variability impact population proliferation? and 3) Why do some floc population distributions converge to self-similarity and others decay to mono-dispersion? Insight into the dominant microscale mechanisms could dramatically change both modeling and consequently control of microbial populations.Micro-organisms suspended in a fluid often do not live as single cells - by collision and separation they combine and recombine in a process called flocculation. These microbial communities exist everywhere from the laboratory to the ocean and the tendency to flocculate has a surprising impact on human life. For example, industrial biotechnologies based on cell cultures (e.g., in the manufacturer of proteins as drugs) rely heavily on predictions of the physical properties of microbial communities. Bacterial clusters are used in municipal sewage treatment plants across the country as an environmentally sustainable part of cleaning human and industrial wastewater. Moreover, bacterial and algal communities in a fluid are an essential part of the bioplastic, biofuel, and biogas industries. In natural settings, the flocculation properties of algae play an important role in algal blooms (and thus in the resultant negative economic and health impacts). The investigator and his colleagues develop and study mathematical models of flocculation and perform experiments to validate predictions of the distribution of cluster sizes and growth rates. This project aims to transform scientific understanding of microbial flocculation from one based upon simplified, idealized models of clusters to one based on microscale mechanistic and metabolic first principles. Advances in our understanding of the population behavior of these microbial aggregates could lead to dramatic improvements in such diverse societal challenges as biofuel production efficiency, sustainable means of handling wastewater, and management of oceanic algal blooms.