Date of Award


Degree Type


Degree Name

Master of Science (MS)


Microbiology and Immunology


Biofilms are an important area of medical research because bacterial biofilms can form on implants such as catheters and are highly resistant to antibiotics and other antimicrobials. The symbiosis between Vibrio fischeri-Euprymna scolopes, is good model to study biofilm. V. fischeri has 18 gene polysaccharide locus, syp, that is required for biofilm formation and colonization. A recent mutant study suggested the possibility that cysteine biosynthetic genes were involved in biofilm formation by V. fischeri, including cysH, cysJ, cysK, and cysN. My results supported a role for cysK and, to a lesser extent, cysH in biofilm formation. Finally, I have data that suggest a role for cysK in early symbiotic colonization by V. fischeri. When squids were inoculated with a V. fischeri cysK mutant for short incubation time, little colonization occurred. In contrast, when the squid were inoculated with the cysK mutant for an extended period, they became readily colonized.

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