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
Predatory bacteria evolved to hunt, attack, and digest other bacteria. They are found in a wide range of environments, including soil, freshwater lakes and streams, oceans and estuaries, and even animal guts. We aren’t yet sure about the ecological roles of predatory bacteria in these environments, but initial studies indicate that they may shape microbial communities. In addition, studies using animal models have shown that predatory bacteria can reduce pathogen loads without toxicity to the animal host, suggesting that we may be able to use these tiny predators in clinical therapies to combat drug-resistant bacterial infections.

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

Our lab is using a combination of computational and wet lab techniques to reconstruct how the predatory lifestyle evolved in bacteria and to define molecular mechanisms governing variation in predation. We have isolated and sequenced predatory bacteria from different environments throughout Rhode Island and the surrounding area. We are using comparative genomics to examine the evolution of different gene families in these predatory bacteria, and we are assaying predatory phenotypes such as prey range and predation efficiency to determine variation in the outcomes of interactions between predatory bacteria and prey.

nc01figure1
Microscopy of Bdellovibrio sp. NC01 isolated from soil collected at a bioswale on the Providence College campus. (A) Small, comma-shaped NC01 attack phase cells attached to larger E. coli prey cells. (B) Negative stain electron microscopy of a NC01 attack phase cell. The scale bar is 500 nm. Figure from manuscript submitted to Applied and Environmental Microbiology.

In January 2018, we published a paper in mSphere featuring research by Brett Enos ’16 and Molly Anthony ’18 on saltwater-adapted predatory bacteria that Brett isolated from Mount Hope Bay, RI. Using comparative genomics, we identified two regions in the genome where genes were likely acquired from other bacteria by horizontal gene transfer. We also showed that this isolate of predatory bacteria was able to attack and kill a range of different Gram-negative bacteria, including soil bacteria and E. coli. https://msphere.asm.org/content/3/1/e00508-17

IMG_0736
Brett Enos, Nicole Cullen, and Sean O’Donnell 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 microbiome data analysis to profile bacterial communities of different sites. We are currently collaborating with colleagues at the University of California-Davis to investigate the gut microbiome of titi monkeys, a non-human primate.

In 2018, we completed a project assessing changes in the bacterial communities of a microflush toilet system developed by Steve Mecca and his lab in Engineering-Physics-Systems at Providence College. Claire Kleinschmidt ’18 worked on this project from sample processing to data analysis. In a paper published in PeerJ, we used 16S rRNA amplicon data to confirm the capacity of the toilet system to contain and eliminate fecal-associated bacteria, thereby improving sanitation and public health. https://peerj.com/articles/6077/

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