Trainee Spotlight


Gina Lewin is a postdoctoral fellow in Marvin Whiteley’s lab in the School of Biological Sciences and the Center for Microbial Dynamics and Infection at Georgia Tech. She is passionate about studying how interactions between organisms influence their behavior and their evolution. Since starting her postdoc in 2016, Gina has used her background in microbial ecology and evolution to study microbe-microbe interactions in the oral cavity.

In our mouths, microbes live in complex communities on the surface of teeth (plaque). These microbes are important for human health; not only do oral microbes cause two of the most prevalent diseases, cavities and gum disease, but they also have regular access to the bloodstream where they are implicated in diseases such as endocarditis and cancer. Scientists, including researchers in the Whiteley lab, have shown that microbes in the oral cavity form complex interactions, and importantly, these interactions influence disease.

Specifically, Gina studies how interspecies interactions influence the behavior and virulence of the periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa). In her research, Gina asked: how similar are interactions among microbes in the oral cavity, and beyond? If a microbe interacts a certain way with species A, will it also interact the same way with species B? Further, this project included both oral and non-oral microbes to ask how interactions differ between microbes that are native to the same environment and those that are not. To answer these questions, Gina performed large-scale transposon sequencing analyses to determine the genes that Aa needs to grow (its essential genome) in the presence of 25 other microbes. This work showed that Aa’s essential genome changes drastically depending on the interacting partner. Notably, Aa survived better with non-oral microbes and, in some cases, non-oral microbes considerably alleviated essential gene requirements. Gina was awarded an F32 postdoctoral fellowship through the National Institutes of Health for this postdoctoral work.

Gina grew up in Hopewell, New Jersey. As an undergraduate at Pomona College in California, she discovered her interest in research while studying isopod evolution and the microbial ecology of mud volcanoes. She received a BA in molecular biology from Pomona in 2010 and then joined Cameron Currie’s lab as part of the Microbiology Doctoral Training Program at University of Wisconsin-Madison. Using research approaches ranging from field work to experimental evolution to bioinformatics, Gina contributed to our understanding of how microbes and microbial communities degrade plant biomass in association with insects. Specifically, she showed how insect-associated Streptomyces have evolved to be highly cellulolytic. In addition, she studied cellulose degrading microbes from the refuse dumps of leaf-cutter ants, uncovering dynamics of competition in these communities during experimental enrichment. She also helped adapt this research to teach about symbiosis, carbon cycling, and biofuels in college and high school classes and at science festivals. When she is not doing science, Gina loves being outside, exploring new cities, and spending time with friends. Find her on twitter @Gina_Lewin


Deanna Beatty completed her PhD at Georgia Institute of Technology where she investigated how small, locally-managed, marine protected areas in Fiji impacted coral-microbe interactions and coral fitness. Deanna received her bachelor’s degree from Northeastern University in Boston, MA in 2008. During her undergraduate program, she pursued opportunities in a variety of research labs, including a molecular biology lab (her first experience pouring agar plates!), as well as performing surveys to quantify fish & bird population responses to blooms of red tide causing dinoflagellate, Karenia brevis, in the Gulf of Mexico.

After her bachelor’s degree, Deanna worked as a research associate at the Scripps Institution of Oceanography in the laboratories of Distinguished Prof. William Fenical, a natural products chemist, and Prof. Paul Jensen, a marine microbial ecologist. During her time at Scripps, she helped discover two new families of bacteria that produce novel alkaloid metabolites. She also helped discover several other new groups of bacteria from marine plants and animals that produced antibiotic effects toward marine pathogens. It was her work at Scripps that fueled Deanna’s interest in pursuing a doctorate in the lab of Prof. Mark Hay, a marine chemical ecologist at Georgia Tech who currently works on tropical coral reefs in the Pacific.

Coral reefs are among the earth’s most biodiverse and productive ecosystems, but are undergoing precipitous decline due to coral bleaching and disease following thermal stress events, which are increasing in frequency, duration, and spatial scale. These effects are exacerbated by local stressors such as overfishing and pollution, collectively causing an increasing number of reefs to shift from coral to macroalgal dominance. These stressors can harm or kill corals through diverse mechanisms, including alterations in how corals interact with microorganisms. By employing a variety of field sampling and field experimental approaches, Deanna investigated consequences of local protection from fishing and coral versus macroalgal dominance on coral survival, anti-pathogen defense, and coral microbiomes within paired algal dominated fished areas and coral dominated marine protected areas (MPAs) in Fiji.

Deanna worked with coral microbiologist, Prof. Kim Ritchie to develop a simple bioassay to test for coral defense against a coral bleaching pathogen in the lab. These techniques, while commonplace in the biomedical field for drug discovery, had not been implemented in field of coral reef ecology. Three stony corals that commonly occur in both the protected and fished areas exhibited defenses toward the thermally-regulated coral bleaching pathogen Vibrio coralliilyticus. However, these defenses were compromised by elevated bioassay temperatures and pathogen density. For a bleaching susceptible but ecologically important acroporid coral (this genus comprises ~25% of all Pacific corals), its anti-pathogen defense was compromised when the coral grew within macroalgal dominated fished reefs versus the coral dominated protected reefs. These findings show that local management can make some corals more resistant to global stressors and that conservation efforts can impact critical foundation species, such as Acroporid corals, in ways that are nuanced and not visible to the naked eye.

Deanna is now a post-doctoral fellow in Prof. John Stachowicz’s marine ecology lab at UC Davis. She will be investigating the role microbes may play in eelgrass wasting disease along a latitudinal gradient from San Diego to Alaska. This is a collaborative project funded by NSF with the Smithsonian (Dr. Emmett Duffy), Cornell (Prof. Drew Harvell), and UC Davis (Prof. John Stachowicz).


Senior Biology major Holly Nichols has been busy at Tech – she’s earned a 4.0 GPA, ventured across the equator for GT’s Pacific Study Abroad Program, spent free time caving, and worked for 3 years as an undergraduate researcher. As a sophomore Holly took Microbiology and then as junior Molecular Microbiology, where she was immersed in experimental design and bacterial genetics, and learned that serendipitous discoveries often occur because “chance favors the prepared mind”, a quotation from pioneering microbiologist Louis Pasteur. In 2016, Holly joined the lab of Dr. Brian Hammer, a Biological Sciences faculty member in the CMDI. Over the next several years Holly launched several projects studying the waterborne pathogen Vibrio cholerae. Like others in the lab Holly studies a toxic harpoon called a Type 6 Secretion System (T6SS), which V. cholerae and many other microbes wield to kill competitors.

Standard protocols with nutrient-rich medium have reproducibly documented ignominious defeat of timid E. coli in lab death matches against T6 V. cholerae killers. But in January 2018 Holly initiated a slightly modified experiment using minimal medium that required the selection of certain ingredients. To her surprise, Holly observed that the mighty V. cholerae appeared unable to kill the E. coli underdog when a particular component was added to the minimal medium. Holly recounts “I assumed I had made a mistake”. But that same ingredient also had the same effect when added to rich medium. After countless replicates and protocol modifications, Holly discovered that indeed addition of one particular ingredient endows E. coli with the ability to withstand attacks by V. cholerae killers.  Holly’s collaborator, Gabi Steinbach, in Dr. Peter Yunker’s physics lab, agrees. Using fluorescence microscopy, Gabi sees that E. coli grown with this additive are largely immune to the wrath of cholera and happy replicate along with their competitor, taking up space and resources. The question remaining is – How is E. coli doing this? Days before commencement, Holly and her graduate mentor Cristian Crisan were busily testing a hypothesis that in response to this additive E. coli can alter its outer surface coat to defend itself, like other microbes that beef up their armor to protect against viral infection or the host immune system. Right now at the early stages of this project, Holly and Dr. Hammer are not revealing the nature of that additive. Perhaps Holly’s surprising result has uncovered that for unassuming E. coli and maybe other bacteria, the best offense is a good defense.

Where is this intelligent and adventurous Jacket off to next? Holly will be exploring lava tubes in Hawaii this summer before beginning a lab technician position at the University of Tennessee. In fall 2020, Holly will embark on a PhD program in microbiology at the University of Wisconsin-Madison.  As CMDI co-director Frank Stewart noted after seeing Holly’s thesis presentation “Her work is everything we should be striving for in our students.  Logical/thorough experimental design, exciting results, and clear next-step questions.” Knoxville and Madison are in for a treat.