Research in the Hammer Lab

Our lab studies microbial interactions at scales that span genes and genomes, regulatory networks, cells, populations, and communities. Harmful and beneficial bacteria are genetically encoded with regulatory networks to integrate external information that tailors gene expression to particular niches. Bacteria use chemical signals to orchestrate behaviors that facilitate both cooperation and conflict with members of the communities they inhabit. Our works focuses on the waterborne pathogen Vibrio cholerae, which causes the fatal diarrheal disease cholera in humans and also resides in aquatic settings in association with with other animals and surfaces like crab shells and zooplankton molts composed of chitin.

Cooperation in microbial systems.

Computational and experimental methods are coupled to discover components of the regulatory network controlled linking signals including chitin, quorum sensing molecules, and nutrient starvation to activities such as natural transformation for the uptake of external DNA, secretion of chitin-degrading enzymes, and production of a Type VI secretion system weapon for killing neighboring cells. These studies will define the role that environment and genetics play in genome evolution for this important marine pathogen.

 

Conflict in microbial systems.

Ecology, genomics, and evolutionary approaches are used to explore the role that contact-mediated antagonism plays in structure and diversity of microbial communities in environmental and host settings. Our current focus is on the Type VI secretion system, a bacteria weapon that Vibrio cholerae and other bacteria deploy to deliver toxic payloads into neighboring competitors and prey.

 

Engineered signaling systems for bio-inspired molecular communication.

In an effort to understand the limits of chemical communication, we engineer E. coli transmitter cells that make Vibrio quorum sensing signal molecules, and E. coli receiver cells that encode receptors that respond by producing green fluorescent protein. The synthetic QS circuits we design manipulate chemical communication and are used to validate mathematical models of cell signaling within engineered microfluidic devices. (see MoNaCo project on the links page)