About the Williams Lab

The Williams lab at Providence College has two research tracks: predatory bacteria and the microbiome. Read on to learn about our projects within these two tracks.

Predatory bacteria
Bacteria are the most diverse form of life on the planet. Within a closely related group of bacteria, such as the gamma-proteobacteria, there is an incredible range of bacterial lifestyles, including commensals found in the human gut, opportunistic pathogens of animals, bioluminescent bacteria that colonize squid, biofilm-forming bacteria and predatory bacteria. How did all this diversity in bacterial lifestyle evolve? How do the associations between bacteria and other organisms shape life?

Transmission Electron Microscopy (TEM) image of a Bdellovibrio bacteriovorus cell attacking a Shewanella cell. Image credit: Mark O. Martin, University of Puget Sound
Transmission Electron Microscopy (TEM) image of a Bdellovibrio bacteriovorus cell attacking a Shewanella cell. Image credit: Mark O. Martin, University of Puget Sound

Our lab uses predatory bacteria as a model system to investigate these and other questions about bacterial lifestyle and the evolution of symbiotic associations. Predatory bacteria eat other bacteria. Researchers have described predatory bacteria in many different taxonomic groups, showing that predatory bacteria have evolved independently multiple times. Bacteria exhibit a variety of predatory strategies, such as the “wolfpack” strategy used by Myxococcus xanthus and the cell invasion strategy used by Bdellovibrio bacteriovorus.

Below is a video of a Bdellovibrio cell dividing within an E. coli prey cell after invasion. (Video credit: Liz Sockett, University of Nottingham, and the Biotechnology and Biological Sciences Research Council)

To investigate our research questions, we use a combination of computational and wet lab techniques. We take advantage of recent advances in genome sequencing technology to investigate the variation and evolution of predatory bacteria genomes. We also use molecular biology techniques to understand features of the predatory lifestyle, such as the range of prey accessible to particular predatory bacteria.

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Sean O’Donnell, Nicole Cullen and Brett Enos present their research at the national American Society for Microbiology General Meeting in Boston in June 2016.

In October 2016, I gave a research seminar on our current work with predatory bacteria. Students have isolated strains of predatory bacteria from an estuary, soil, an urban stream and the built environment. We’re working to test the prey range and predation efficiency of these isolates. Check out the slides to see our latest: uri_102816

In December 2015, I talked about our predatory bacteria research in an online microbiology seminar series. Check out the video below to learn about these projects.

Microbiome
In recent years, our view of the microbial world has shifted from an antagonistic relationship aimed at eradicating “germs” to an ecological perspective that considers the web of interactions among microbes and other organisms, including us. We know that microbes are essential for the health and development of humans, other animals and plants. The microbial communities occupying a particular habitat, whether it is our bodies, plant root systems, or man-made structures, are referred to as the “microbiome” of that site. Advances in sequencing technology and bioinformatics methods have enabled us to explore these microbiomes in more detail than ever before. In the Williams lab, we use 16S rRNA gene sequencing to profile bacterial communities of different sites. We are currently working on three different projects: (1) investigating variation in the gut bacteria of titi monkeys, a non-human primate, (2) exploring how circadian rhythms affect the gut bacteria of rats, and (3) assessing changes in the bacterial community of a microflush toilet system (developed by Steve Mecca and his lab in Engineering-Physics-Systems at Providence College).

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