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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Rosser_thesis.pdf

Sarah Joyce Rosser (18495273) 03 May 2024 (has links)
<p dir="ltr"><i>Serratia marcescens </i>is a bacterium with a ubiquitous environmental distribution and the ability to cause opportunistic infections. This research explores three different group behaviors in <i>S. marcescen</i>s. These are biofilm formation, microbial hitchhiking, and responses to cannabinoid-induced stress. To study biofilm development, we used a crystal violet assay to measure biofilm and compared that to the bacterial growth of those cultures. We looked at the role of nutrients and temperature in biofilm produced by <i>S. marcescens</i> and tested four <i>S. marcescens</i> strains. We found that there were differences in the ratio of biofilm to growth when <i>S. marcescens</i> was grown in different media. The exact relationship between temperature and media composition requires more information than could be attained from these studies. Next, we wanted to investigate whether <i>S. marcescens</i> could also utilize movement of other, more highly motile species of bacteria through a process called microbial hitchhiking. <i>S. marcescens</i> was grown with a highly motile <i>Paenibacillus</i> sp. isolate. <i>S. marcescens</i> was tracked by the red pigment that it produces. It was observed that <i>S. marcescens</i> consistently spread farther across a surface when it was co-cultured with <i>Paenibacillus</i> sp. than when grown alone. This was repeated with three other <i>S. marcescens</i> strains and three different species of <i>Paenibacillus.</i><i> </i>Hitchhiking behavior was observed in all cases. To understand the mechanism by which <i>S. marcescens</i> hitchhikes on <i>Paenibacillus </i>spp., a <i>S. marcescens </i>flagellar mutant was used. Even in the absence of a flagellum, <i>S. marcescens</i> was still able to hitchhike implying that another mechanism must be involved. Finally, we evaluated the response of <i>S. marcescens </i>to cannabidiol (CBD) a phytocannabinoid with antimicrobial and antibiofilm properties, though it has limited potency against Gram-negative bacteria like <i>S. marcescens</i>. We found that CBD did not kill <i>S. marcescens </i>nor did it affect its biofilm development. Interestingly, <i>S. marcescens </i>cultures showed enhanced pigment production in response to high-dose CBD exposure compared to vehicle controls. This response was also observed with exposure to three additional phytocannabinoids. Results from these studies add to our understanding of how <i>S. marcescens</i> can access new areas and persist in a broad range of environments.</p>

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