Bacteria have developed a variety of strategies to find and consume the substrates necessary for both the cell’s energy-consuming processes and for the additional biomass needed to replicate. A greater understanding of the diversity and regulation of these strategies can provide us with a number of insights relevant for a variety of applications, from predicting bacterial population dynamics and thus carbon-cycling rates in the ocean to bio-engineering bacteria into microscale robots. Here I use toy, mechanistic models of single-cell metabolism that allow me to quantify the costs and benefits of various nutrient uptake strategies. I find that: (i) a sensing-uptake trade-off governs E. coli's regulation of maltose uptake and chemotaxis to maltose; (ii) a rate-affinity trade-off in nutrient transport systems governs the speciation of marine oligotrophic and copiotrophic heterotrophs; and (iii) an exploration-conservation trade-off governs the prevalence of motility in the marine microbial world. This work thus provides new understanding of how both phenotypic diversity and cellular regulation are governed by trade-offs for maximizing growth rate in different environments.
Thesis Supervisors: Emilio Frazzoli and Roman Stocker, ETH Zurich
Thesis Committee: Naomi Levine, USC. Munther Dahleh and George Verghese, EECS, MIT