You and I: The Effects of Intra- and Inter-Species Interactions on Microbial Biofilms, Growth, and Morphology

Humanity is shaped by its relationships with microbes. From bacterial infections to the production of biofuels, industry and health often hinge on our control of microbial populations. Understanding the physiological and genetic basis of their behaviors is therefore of the highest importance. To this end I have investigated the genetic basis of plastic adhesion in Saccharomyces cerevisiae, the mechanistic and evolutionary dynamics of mixed species biofilms with Escherichia coli and S. cerevisiae, and the induction of filamentation in E. coli. Using a bulk segregant analysis on experimentally evolved populations, I detected 28 genes that are likely to mediate plastic adhesion in S. cerevisiae. With a variety of imaging and culture manipulation techniques, I found that particular strains of E. coli are capable of inducing flocculation and macroscopic biofilm formation via coaggregation with yeast. I also employed experimental evolution and microbial demography techniques to find that selection for mixed species biofilm association leads to lower fecundity in S. cerevisiae. Using culture manipulation and imaging techniques, I also found that E. coli are capable of inducing a filamentous phenotype with a secreted signal that has many of the qualities of a quorum sensing molecule.

Race, Power and Economic Extraction in Benton Harbor, MI

My dissertation investigates twin financial interventions—urban development and emergency management—in a single small town. Once a thriving city drawing blacks as blue-collar workers during the Great Migration, Benton Harbor, Michigan has suffered from waves of out-migration, debt, and alleged poor management. Benton Harbor’s emphasis on high-end economic development to attract white-collar workers and tourism, amidst the poverty, unemployment, and disenfranchisement of black residents, highlights an extreme case of American urban inequality. At the same time, many bystanders and representative observers argue that this urban redevelopment scheme and the city’s takeover by the state represent Benton Harbor residents’ only hope for a better life. I interviewed 44 key players and observers in local politics and development, attended 20 public meetings, conducted three months of observations, and collected extensive archival data. Examining Benton Harbor’s time under emergency management and its luxury golf course development as two exemplars of a larger relationship, I find that the top-down processes allegedly intended to alleviate Benton Harbor’s inequality actually reproduce and deepen the city’s problems. I propose that the beneficiaries of both plans constitute a white urban regime active in Benton Harbor. I show how the white urban regime serves its interests by operating an extraction machine in the city, which serves to reproduce local poverty and wealth by directing resources toward the white urban regime and away from the city.