Fundamental studies of the foodborne pathogen Yersinia enterocolitica and Applied food systems research, teaching and outreach in Vietnam and Cambodia

This dissertation explores various aspects of microbiology that affect human health and wellbeing as well as issues related to international food systems. Chapters one and two focus on fundamental natural sciences research of a foodborne bacterial pathogen, Yersinia enterocolitica. Chapter three details the application of natural and social sciences in food systems research, teaching and outreach in two developing countries, Vietnam and Cambodia.;This study is the first to characterize any of the novel Y. enterocolitica Ysp effectors. The collection of observations and results presented here show YspI displays unique functionality in mammalian cells by targeting a key regulator of numerous cellular processes, focal adhesion kinase (FAK). Analysis of the interaction between YspI and FAK, and the effect this has on normal mammalian cellular processes, provides insight into how YspI may contribute to colonization of Y. enterocolitica in mammalian hosts.;The second chapter of this dissertation explores the function of carbon storage regulator A (csrA) in Y. enterocolitica. CsrA, in other bacterial species, is a post-transcriptional regulator of many specific genes that coordinates a myriad of physiological activities. The study reported here mapped the precise location of the transposon insertion in csrA. Genetic complementation restored disruptions in motility and the YplA export phenotype, which confirmed this mutation disrupted CsrA function. It was determined mutation of csrA affected expression of yplA as well as flagellar T3SS dependent export and motility by altering expression of the master regulators flhDC . Mutation of csrA also resulted in increased sensitivity of Y. enterocolitica to various osmolytes, temperatures and antibiotics. The results of these studies in Y. enterocolitica are the first to show CsrA may be an important target when attempting to control growth of bacteria in certain environments where it may threaten human health and wellbeing. This report also provides perspective on how the Csr system in different bacterial species is susceptible to adaptation to particular environments and bacterial lifestyles.;Chapter three details a collection of international teaching, research and outreach activities. A combination of natural and social sciences were applied in Vietnam and Cambodia to various aspects of the food systems in these developing countries. Part one of this chapter details Action Research in the Agricultural Sciences, an undergraduate course that was a designed collaboration between UC Davis, Nong Lam University in Ho Chi Minh City, Vietnam, and Hanoi University of Agriculture, Vietnam. This course guided Vietnamese students through senior research projects focused on agricultural development and applied research in collaboration with peri-urban vegetable farmers.;Part two of this chapter focuses on microbiology research in different areas of the food systems in Vietnam and Cambodia. Another component of the work presented here describes some of the challenges researchers face in efforts to identify and characterize microbial pathogens in the food supply in Cambodia.;The final part of this chapter describes research and outreach to address various issues that affect development of the food system in Cambodia. The work conducted as part of this dissertation included outreach to leading farmers within the communities as well as representatives from local markets to address these challenges. Through the entire process, a market-driven value chain for safe vegetables was developed. Overall, chapter three illustrates how a combination of natural and social sciences were applied to development activities that addressed various aspects of the food systems in Vietnam and Cambodia. (Abstract shortened by UMI.).