The SpatialEcology of Microbes

作     者：Wetherington, Miles T. 

作者单位：Pontificia Universidad Catolica de Chile 

授予年度：2021年

摘      要：Guided by cell biophysics experimentation and equipped with toolsets from theoretical ecology, the aim of my thesis is to explore the ways in which spatial structure influences the dynamics and distributions of microbial cells, populations and communities. In my first project, we highlighted range expansion experiments of a colicin producing-colicin sensitive *** community on solid agar; The process of colony formation is driven by colicin production, cell lysis and division all driving the dynamical structure and ecological composition of the colony. Making analogies to percolation theory from statistical physics, we were able to develop a spatial model to quantify regimes of strain coexistence, competitive exclusion and extinction. Next we aimed to understand the spatial conditions under which microbial common goods games could persist. A particular bacterial system motivating this study was Pseudomonas aeruginosa, which excretes a costly ‘iron-scavenging’ compound (siderophore) in order to bind and transport iron across the cell membrane. This compound represents a common-pool resource, susceptible to exploitation by nearby bacteria free from producing this metabolically costly resource. With this system in mind we asked the following question: what spatial conditions permit these common-pool resources to be monopolized by a cooperator strategy in competition with an exploiter strategy? By developing a stochastic spatial model, we quantified the phase transition from monopolized to exploited and predicted which circumstances to expect coexistence between niche constructing and exploiter strategies as a result of differences in niche monopolization and colonization rates, respectively, and when to expect a collapse of the niche and a ‘tragedy of the commons’. Following this work, I began to apply newly acquired expertise in microfluidics, microfabrication techniques, microscopy and experimental cell biophysics in order to observe and study the spatial colonizat