Karatan Lab

Effect of vibriobactin synthesis on Vibrio cholerae biofilm formation and norspermidine production

Vibrio cholerae is a pathogenic bacterium responsible for the acute diarrheal disease cholera, which infects 3-5 million people each year, leading to severe dehydration and even death if left untreated.  The ability for bacteria to form biofilms is a potential survival strategy within a host organism.  Biofilms are multi-layered cellular communities encased in an exopolymeric substance and can form on abiotic and biotic surfaces.  Biofilms offer several advantages to bacteria within a host organism including protection from antibiotics, host immune responses, lack of nutrients, and unsuitable environments.  In V. cholerae biofilms are regulated by a number of environmental signals including the polyamine norspermidine, norspermidine has been shown to up-regulate biofilm formation and is synthesized by the nspC gene.  My research is focusing on understanding how iron availability regulates transcription of the nspC operon and biofilm formation in V. cholerae.

                Vibrio cholerae has multiple iron acquisition systems one of which relies on the production of vibriobactin, a catecholamide siderophore containing a norspermidine backbone.  Vibriobactin is produced under low iron conditions in order to sequester ferric iron (Fe(III)+) from the environment.  Due to the link between norspermidine and vibriobactin it is hypothesized that iron availability will regulate vibriobactin synthesis, norspermidine synthesis and biofilm formation in V. cholerae.  I hope to better understand V. cholerae phenotypic response by quantifying nspC expression in parallel with biofilm formation and vibriobactin synthesis under both iron replete or iron deplete conditions.  I will also be exploring the effect of iron availability on biofilm architecture using SEM.