USE OF NEXT-GENERATION SEQUENCING TOOLS TO EXPLORE THE REGULATORY NETWORK OF LISTERIA MONOCYTOGENES
Listeria monocytogenes presents a challenge to food safety and public health worldwide. This foodborne pathogen is known to cause listeriosis, a serious invasive disease that particularly affects susceptible populations including immunocompromised individuals, newborns, pregnant women, and elderly people. New approaches for prevention and treatment of listeriosis require better understanding of mechanisms that enable L. monocytogenes to survive and thrive under a wide range of environmental conditions. One key regulatory mechanism of this Gram-positive bacterium involves the differential expression of different sets of genes by alternative sigma factors. In these studies, we employed next-generation sequencing tools to explore the regulatory network controlled by two alternative sigma factors, σB and σH. Specifically, our studies focused on (i) the regulatory roles of σB and σH, in the absence of other alternative sigma factors, (ii) the contribution of σB regulon members in important biological processes, and (iii) the development of a new transposon sequencing tool in L. monocytogenes. Our RNA sequencing data indicate that σH regulates a number of competence genes; We also found that in addition to stress response and virulence, σB has a broad role of resilience. For instance, σB regulates the metabolism of macronutrients and micronutrients to succeed in the intracellular environment where many nutrients are limited. Lastly, we designed a vector for a new transposon delivery system in L. monocytogenes. Overall, these findings provide a more complete picture of the regulatory network in L. monocytogenes.
Food science; RNA-Seq; Listeria monocytogenes; regulon; sigB; sigH
Grohn, Yrjo Tapio; Turvey, Calum G.
Food Science and Technology
Ph. D., Food Science and Technology
Doctor of Philosophy
dissertation or thesis