The evolution of Vibrio cholerae in aquatic environments

Until recently, research on V. cholerae had a strong focus on the human disease caused by this bacterium. The reason for this is our desire to fight cholera by developing vaccines or finding efficient treatments that can eliminate or at least shorten the massive diarrhea associated with this disease. However, even with these goals in mind, it is worth taking a step backward and think about how V. cholerae gained pathogenic traits in the first place. By looking at the environmental lifestyle of V. cholerae, we recently discovered that chitin surfaces induce natural competence for genetic transformation in V. cholerae. Natural competence is a well-known phenomenon and refers to the physiological state in which a bacterium is able to take up free DNA from its surrounding and to incorporate it into its genome. As an important mode of horizontal gene transfer (HGT), natural competence enables V. cholerae to acquire new genes, including those that specify pathogenic traits or are beneficial for the adaptation to new habitats. Not surprisingly, other species of the genus Vibrio also respond to chitin by inducing natural competence.

The main research aims of our group at the Swiss Federal Institute of Technology Lausanne (EPFL) are therefore:

1. To elucidate the regulatory network that drives natural competence and transformation in V. cholerae (using molecular biology-based experimentation and biochemistry).
2. To better understand the DNA-uptake process, which involves a macromolecular protein complex (through the use of cellular microbiology-based approaches combined with biophysical experimentation). 
3. To test for non-human hosts of V. cholerae and investigate such host-microbe interactions (using bacterial genetics and time-lapse confocal microscopy). 
4. To decipher to role of the so-called virulence factors in the bacterium’s primary habitat, the aquatic environment (using engineered strains of V. cholerae and diverse microscopy techniques).    

More information and details about our recent publications please visit our webpage: http://blokesch-lab.epfl.ch