Katherine Ennis ’04 Wins Prestigious Women in Science Award
The academic freedom she learned at Colby has served her well as a postdoctoral fellow applying theories of ecology to microbiology
Japanese woodblock prints made a splash with the artists of Paris in the late 1800s, notably Mary Cassatt and Edgar Degas. Many painters of the period in France were captivated by the flatness of the compositions and the radical off-angle views the Japanese artists had employed, and they adapted these dynamic characteristics to invigorate the look of their paintings. It’s an example of how ideas imported from one locale to another can spark innovation.
In her current research as a postdoctoral fellow at the University of California, Berkeley, Katherine Ennis ’04 is injecting a concept from her first field of study at Colby, ecology, into a new one, microbiology, and in doing so has found a line of inquiry that is generating some surprising and promising results.
Ennis recently won a coveted L’Oréal USA For Women in Science prize, which includes a $60,000 award that will support her research in plant and microbial biology, as well as integrative biology. The award recognizes women at the forefront of scientific innovation, and Ennis is among five 2024 recipients who represent a range of disciplines and research. Each year, the For Women in Science Program provides grants to postdoctoral researchers to advance their research and careers. Since 2003, the program has supported more than 100 women scientists and awarded more than $5 million in grants.
Prior to her postdoctoral appointment, Ennis was a dual major at Colby, starting in government and adding environmental studies after a transformational research trip to Anguilla during Jan Plan with the late David H. Firmage, the Clara C. Piper Professor of Biology and Environmental Studies, Emeritus, and Russ Cole, Oak Professor of Biological Sciences, Emeritus.
A ‘magical experience’ at Colby
“It was a magical experience, and very exciting and fun,” Ennis recalled. “We were given a freedom that I just don’t think you get when taking most classes to explore and see things and investigate.”
That freedom to explore set the path for her career and her interdisciplinary approach to research. From Colby, Ennis studied ecology for her master’s at the University of Michigan and earned a doctorate at the University of California, Santa Cruz. Her move into microbial biology at UC Berkeley in 2020 was her first foray into the field, and a step toward her goal of applying theories of ecology to microbiology to unearth new insights.
In studying community ecology, Ennis researched how one species may have an indirect but profound influence on another species. “We call it a non-consumptive effect,” Ennis said, citing the example of the behavioral influence of a big cat like a lynx on a rabbit population. Even if the lynx does not have the direct effect of eating the prey, its presence changes the rabbits’ behavior by forcing them into hiding and curtailing their foraging, which reduces their fitness.
What if, thought Ennis, phages—viruses ubiquitous in the natural world that infect bacteria and reproduce within them—could affect bacteria indirectly, without actively infecting them? It was a different way of looking at microbiological effects.
“I’m a community ecologist by training and came into the microbiome world as a postdoc. So I wasn’t doing this work as a Ph.D. student, although I was in biology and environmental science. I think having this perspective was, to be perfectly frank, a little bit out of the box,” Ennis said. “Rather than the typical microbiome perspective, looking at things pairwise or how does this one thing affect this one other thing, in community ecology, we look at what happens at the macro level of an ecology.”
Bringing phages and bacteria together
Ennis began this research with in vitro experiments, moving later to plants, bringing phages and bacteria together in environments where the phages are present but are not actively replicating in cells—the threshold for infection—which are called non-host cells. “This is important because it’s what happens in the real world. These viruses are everywhere, and wherever you would find bacteria, they are often found in higher abundances than the bacteria, and very frequently you find them without a host,” Ennis explained. “The question for me has been, well, what else is happening beyond just infection?”
So far, across a variety of bacterial species, Ennis has found consistently that even when a phage was not infecting bacteria directly, and with no evidence of the phage replicating, there is a decline in the growth of the bacteria. “It’s a relatively small effect on fitness, but it is significant,” Ennis says.
‘I think ultimately our legacy as a scientist is as a mentor. Helping people figure out what drives them as a scientist and how they can find their niche would be pretty spectacular. Your science lives on through those people as much as anything.’
Katherine Ennis ’04
To learn more, Ennis then took a group of the bacterial species and disabled specific genes within the bacteria, referred to as a knockout of the gene, and exposed the bacteria to phages that do not infect them to detect changes in the bacteria. Among the results so far, Ennis found that when a regulatory component in cells in the bacteria was knocked out, the cells did markedly better when there was no phage, but did terribly in the presence of the non-infecting phage. “What this shows is that there’s a high cost to having this particular regulator if there is no external pressure from the phage,” she says.
Ennis’s phage research could play a part in a newly resurgent area of investigation called phage therapy, which introduces phages to control dangerous bacteria. The idea has been around for more than a hundred years but was displaced early on by antibiotics. Phage therapy is getting a second look now that superbugs—bacteria resistant to antibiotics—are becoming more prevalent.
“There are some issues with phage therapy still, but it is being employed as an end-use case for people that have really strong antimicrobial-resistant strains, and with some success,” Ennis said. “My research specifically is looking at how all of these phages that you inject into somebody might affect the rest of the microbiome, in the gut, for instance, and looking at things like that which we haven’t been investigating as yet.”
Beyond research, part of Ennis’s intent for the L’Oréal award focuses on mentorship. She credits her own past professors for helping her bring a polymath’s attitude to her own research and encouraging her to study across fields. “They really looked beyond their own field for inspiration, and were avid readers beyond scientific journals,” she said.
In her own mentoring, Ennis is promoting the presence of women and others who are underrepresented in upper levels of academia, and she will hold workshops and do individual mentoring to that end.
“I think ultimately our legacy as a scientist is as a mentor,” she said. “Helping people figure out what drives them as a scientist and how they can find their niche would be pretty spectacular. Your science lives on through those people as much as anything.”
