Special Seminar - Benjamin Kostiuk: Changes in competitiveness of the bacterium Vibrio cholerae across pandemics

Abstract:

The Gram-negative bacterium Vibrio cholerae is the causative agent of the diarrheal disease cholera. Unknown factors led to the decline of 6^th pandemic classical strains and the spread of El Tor strains giving rise to the current 7^th pandemic. The type six secretion system (T6SS) is one mechanism that allows V. cholerae to persist in the environment and in the host. We investigated the ability of classical V. cholerae strains of the 2^nd and 6^th pandemics to engage in microbial competition and tested their defense against T6SS-mediated attack compared to their 7^th pandemic counterparts. Our results suggest that classical V. cholerae experienced sequential mutations in T6SS genetic determinants that disadvantaged them as microbial competitors. Analysis of available V. cholerae genomes over a timeline spanning 150 years provides insight into the role of T6SS in bacterial competition across pandemics.