Date of Award
Master of Science (MS)
Microbiology and Immunology
Vibrio fischeri bacteria form biofilms that facilitate symbiotic colonization of the Hawaiian bobtail squid, Euprymna scolopes. These host-associated biofilms require production of the SYP polysaccharide. However, it has been difficult to observe robust biofilm formation in vitro in a laboratory setting using wild-type strain ES114; instead, most work investigating syp-dependent biofilm formation has relied on genetically altered strains. Guided by recent findings that increasing calcium induces c-di-GMP (Tischler et al., 2021), a molecule known in other systems to promote biofilm formation, the question was posed as to whether high levels of calcium alone could promote syp-dependent biofilm formation by ES114. Using shaking biofilm, pellicle, and spot plate assays, we observed that ES114 could readily form a biofilm when exposed to high levels of CaCl2. Within 24 hours, shaking cultures formed a ring indicative of cellulose biofilm production, as well as sticky branching structures associated with activation of SYP production. Pellicle assays revealed that ES114 could form cohesive (sticky) syp-dependent pellicles within 24 hours of exposure to high levels of calcium. Although the results were less consistent, ES114 typically produced sticky spots on plates within 5-8 days. Each assay required a different type of media for most efficient biofilm production, an interesting result that could result in further studies. In this research, a variety of gene deletion and overexpression strains were used to determine if previously identified regulators are required for biofilm formation under conditions of high calcium. Overall, this condition presents a new way to reliably induce biofilms in wild type strain ES114, quickly compare the effects of gene deletion or over-expression on biofilm production in vitro, and to investigate mechanisms underlying calcium-stimulated biofilm formation.
Semenchuk, Katia Elizabeth, "Calcium-Mediated Induction of Vibrio Fischeri ES114 Biofilms" (2022). Master's Theses. 4426.
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Copyright © 2022 Katia Elizabeth Semenchuk