The Ohio State University: College of Arts and Sciences

Former Lab Members

Former Postdoctoral Researchers

AllersElke Allers, Ph.D |
Elke arrived in January 2009 from the Max Planck Institute in Germany where her PhD thesis work centered upon using fluorescent in situ hybridization (FISH) to identify particular marine microbial groups, and evaluate their physiological responses to experimental manipulations. Her TMPL research furthered FISH towards the high-throughput exploration of novel microbial lineages and phage-host interactions in marine systems. Following her postdoctoral work with TMPL, she worked at Accelerate Diagnostics, from February 2013 – January 2017. She is currently a self-employed scientist/consultant based in Germany.

Nirmala Bardiya, PhD |
Nirmala joined the Sullivan lab in December 2016. She has extensive experience in wet lab microbiology, biochemistry and molecular biology approaches for studying and developing genetic tools in a variety of prokaryotes, archaea and eukaryotes. In the Sullivan lab, she is developing genetic tools to understand regulation of the phage infection process in Cellulophaga baltica and to help develop phage-therapy as an alternative to antibiotics. In addition, she is interested in discovering host-phage interactions in marine environments using PhageFISH and Fusion PCR. Nirmala is originally from India and carries scientific experiences from working in India, S. Korea, England, and previous assignments in USA. In the past, she has received several international fellowships including UNDP, British Council-Korea, Brain Korea-21 (KOSEF), and Brain Pool visiting scientist from KOFST. Her hobbies include reading, meditation, and providing care at Mother Teresa’s home.

Jennifer Brum, Ph.D |
Jenn’s research focused on marine viral community ecology and the myriad ways in which viruses affect Earth’s ecosystem processes. Her projects included (i) ecology of viruses in the Southern Ocean, (ii) investigating viral ecology and the influence of viruses on biogeochemical cycling in the Eastern Tropical North Pacific oxygen minimum zone, (iii) examining the global distribution of viral communities through the Tara Oceans and Malaspina Expeditions, and (iv) exploring hydrothermal vent viral communities on the Mid-Atlantic Ridge.  She is currently an Assistant Professor at Louisiana State University in the Department of Oceanography and Coastal Sciences.


Vinh Dang, Ph.D |
Vinh finished his PhD in Australia and joined the Sullivan Lab in October 2013. During his time with the lab, he focused on several projects, which are associated with phageFISH and viral tagging. The main project was collaborated with a number of researchers to help quantify nutrient-virus interaction and their impact on marine biogeochemistry by addressing 1) how nutrient availability affect viral infection dynamics and 2) how virally-encoded genes contribute to nutrient uptake during infection. He is currently the Dean of Faculty of Aquaculture at Ha Long University.

Katarzyna Danis-Wlodarczyk, PhD |
Kasia’s PhD focused on characterization of lytic bacteriophages infecting Pseudomonas aeruginosa and their peptidoglycan and exopolysaccharide degrading enzymes. She obtained her PhDs in Bioscience Engineering from KU Leuven in Belgium and Biological Sciences, specialization Microbiology, from The University of Wroclaw, Poland. She joined the Sullivan and Wozniak labs in 2018, where she studies phage therapy, characterizing Pseudomonas and Staphylococcus phages.

DengLi Deng, Ph.D |
Li arrived in Oct 2008 from the University of Bristol where she studied freshwater cyanophages lfor her PhD. At TMPL, she has focused on three projects: (1) Synechococcus cyanophage population genomics along the Monterey Bay Line67 transect, (2) freshwater cyanophage comparative genomics, and (3) on a flow cytometry “viral tagging” project. Currently, she is a scientist at the Institute of Virology at Helmholtz Zentrum Muenchen, German Research Center for Environmental Health.


Melissa Duhaime, Ph.D |
Melissa arrived May 2010 from the Max Planck Institute in Germany where her PhD thesis work explored viral genomics and metagenomics. As a post-doc at TMPL from May 2010 to November 2011, Melissa worked on model phage-host systems (Cyanosiphophage P-SS2, Pseudoalteromonas phages) and phage RAST, as well as the development of the linker amplification method. She is currently an Assistant Professor of Ecology and Evolutionary Biology at the University of Michigan. The Duhaime Lab

EmersonJoanne Emerson, Ph.D |
Joanne uses meta-omic, bioinformatic, and ecological techniques to study feedbacks between viral and microbial communities and their influences on biogeochemistry and ecosystem ecology in a variety of environments, particularly soil. She completed her Ph.D. in 2012 in Jill Banfield’s lab at UC Berkeley, where she used metagenomic techniques to study viral population dynamics and community ecology in hypersaline lakes and predicted the environmental impacts of microbial communities in the terrestrial deep subsurface with implications for geologic carbon sequestration. Her first postdoctoral position was in Noah Fierer’s lab at the University of Colorado, Boulder, where she studied bacterial, archaeal, and fungal ecology in the atmosphere and the built environment and developed metagenomic techniques for studying viral assemblages in soil. Recent work as a postdoctoral researcher in Matt Sullivan’s and Virginia Rich’s labs at The Ohio State University has involved studying viral and microbial controls on greenhouse gas emissions in thawing permafrost peatland soils and nearby lake sediments. In the near future, Joanne plans to study virus-host dynamics in a variety of natural and agricultural soils. Joanne’s full profile. The Emerson Lab.

Sheri_FlogeSheri Floge, Ph.D |
Sheri is interested in how marine microbes interact with one another and their environment, the chemical reactions that mediate such interactions and the resulting impact on global elemental cycles. Her Ph.D. research focused on the impact of virus infections on intact, infected eukaryotic marine microbes and included bioinformatic and flow-cytometric screening for persistent (cryptic) infections and combined molecular, chemical and ecological methods to quantify virus-induced biochemical alterations of phytoplankton cells and the resultant impact on copepod grazing. Sheri joined the Sullivan Lab in August 2014 where her projects include using transcriptomics and metabolomics to explore interactions between model systems of viruses, bacteria, phytoplankton and grazers and developing experimental methodology to quantify the role of marine viruses in trophic transfer of carbon. Sheri’s full profile

Photo of ConsueloConsuelo Gazitua, Ph.D |
Consuelo obtained her PhD in molecular genetics and microbiology at the Catholic University of Chile, where she studied the contribution of rhizospheric microorganisms in the establishment of pioneer plants over mine tailings. In her first postdoctoral position she moved to the marine environment, specifically to the East Tropical South Pacific oxygen minimum zone, where she studied the composition and activity of pico- and nanoplanktonic communities with especial focus on the eukaryotic fraction. In October 2015 she joined the Sullivan lab, where she studies the viral communities from the ETSP oxygen minimum zones, analyzing its composition and potential role in biogeochemical cycling. She is currently a research associate in a phage therapy-focused company, Phage Lab, in Chile.

Ann Gregory, PhD |
Ann Gregory is a viral ecologist and population geneticist interested in understanding the role of viruses in human gut microbiome dynamics. Ann received her PhD in Matt Sullivan’s lab at Ohio State University where she studied viruses in the global oceans and human gut. Ann received the EMBO fellowship for a postdoc position in Belgium at KU Leuven under the mentorship of Jeroen Raes, where she shifted gears to focus on bacterial metabolisms in the human gut. After completing her fellowship, Ann moved back to the US to be closer to family and recently re-joined the Sullivan lab for another postdoc to re-focus on viruses. As of early 2024, she is now a Assistant Professor at the University of Calgary, Canada, where she leads a human virome-oriented research lab. Gregory Lab

HargreavesKatherine Hargreaves, Ph.D |
Katherine is interested in how viruses can modulate their bacterial hosts, and the consequences of infection from both the bacterial and virus perspective. She is motivated by discovery-based science, having obtained her PhD at the University of Leicester during which she isolated phages infecting the medical pathogen Clostridium difficile, from environmental sources. While at Leicester, she used next generation sequencing technologies to study bacterial-virus relationships applying whole genome sequencing and transcriptomic analysis for different infection types. She joined the Sullivan Lab to expand into characterising complex viral communities using the model marine system. Her projects include developing new methods to assign new information to viral sequences of unknown function and affiliation, and to investigate the effects of different bacterial-phage interactions in the biosphere.

HolmfeldtKarin Holmfeldt, Ph.D |
Karin arrived July 2010 from Kalmar University in Sweden where she established a Cellulophaga phage collection from the Baltic Sea for her PhD. As a post-doc at TMPL from July 2010 to June 2012, Karin developed a new environmental model system through genome sequencing, virion structural proteomics of representative isolates, and experimental hypothesis testing. She is now an assistant professor at the Linnaeus University Centre for Ecology and Evolution in Microbial model Systems. Karin’s full profile.

Howard2Cristina Howard-Varona, PhD |
Cristina on linkedin
Cristina on Twitter
Cristina obtained her MSc in Biotechnology from the Polytechnique University of Valencia (Spain) and her PhD in Molecular Biology from the University of Arizona (USA). She is interested in understanding the regulation of viral infections in nature, in characterizing the regulation of understudied infections such as the extrachromosomal temperate or inefficient lytic phages, and in developing new environmental model systems to expand the limited diversity of known phage-host systems.  She uses a wide range of techniques, from the more traditional molecular biology and microbiology approaches to single-cell, bioinformatics and ‘omics (transcriptomics, proteomics, metabolomics). She joined the lab as a post-doc in 2015, and her current projects involve understanding regulation of viral infection efficiency in the Bacteroidetes bacterium Cellulophaga baltica, assessing nutrient dynamics impacts on phage-host interactions in a Pseudoalteromonas bacterium, and how we can understand the regulation of phage-host interactions to improve the development of phage therapy. Cristina is interested in studying virocells across organisms and environments. She is currently a Research Scientist in the Sullivan lab where she is involved in multiple projects that include virocell metabolism and ecology.

Ho Bin Jang, D.V.M., PhD |
Ho Bin has been focusing on network construction of viral genomes and translation of the patterns of network topology and connectivity into biological and evolutionary interpretation. His first postdoc position was in Rob Lavigne’s lab at the KU Leuven in Belgium, where he developed an expertise in applying network tools to study large scale virus populations for various bacterial hosts. On February 1st, 2016, he joined the Sullivan Lab where he studies phage-host interactions, particularly for cyanobacteria (i.e., Prochlrococcus or Synechococcus), by employing network tools combined with phageFISH and viral tagging. He is currently a Research Professor in the Department of Microbiology, Institute of Viral Diseases, Korea University College of Medicine in Seoul, South Korea.

RouxSimon Roux, Ph.D |
Simon joined the Sullivan Lab in November 2013 from the Université Blaise Pascal (Clermont-Ferrand, France), where his PhD work focused on the bioinformatics anlaysis of viral metagenomes, from the development of tools dedicated to these datasets, to the analysis and meta-analysis of viromes toward a better understanding of the ecology and evolution of viruses. At the Sullivan lab, his main projects again involve both the development of new tools to process viral genomes and metagenomes, and the analysis of viral signal in large-scale genomics and metagenomics datasets. Overall, these different projects all work toward a better understanding of the “viral dark matter”: the incredibly vast and still largely unexplored set of environmental viruses infecting microbes, with special interest in deciphering the extent of viral diversity in nature, the mechanisms shaping the long-term evolutionary history of viral genomes, and the ecological drivers of these communities in aquatic biomes. Currently, he is a research scientist at the DOE Joint Genome Institute. Simon’s full profile

Lindsey Solden, PhD |
Lindsey Solden, PhD is a postdoctoral researcher that joined the lab in June 2019. She is focused on the annotation and impact of metabolic genes on viral genomes. In her PhD in Kelly Wrighton’s lab she focused on microbial metabolism in the ruminant gastrointestinal tract, with a particular interest in the coordinated degradation of plant material with carbohydrate active enzymes. Currently, she holds a senior scientist role at Epistemix, Inc.

Christine Sun, PhD |
Christine graduated with a BA in Biology with a concentration in Microbiology in 2006 from Cornell University. Her first research project was as an undergraduate in the laboratory of Stephen Zinder, where she investigated temporal patterns of methanogenesis and methanogen composition in different peatlands. Christine obtained her PhD in Microbiology in 2013 from the University of California, Berkeley, where she worked in the laboratory of Jillian Banfield. Her PhD research was primarily computational and she learned how to use different bioinformatic tools to understand and evaluate microbial communities. Christine’s research was focused on metagenomic analyses of CRISPR-mediated host-virus interactions. She continued research into ecological analyses in microbial communities in her first post-doctoral position at Stanford University, where she worked in the laboratory of David Relman. Her work focused on the metagenomic analysis of microbial communities during pregnancy in humans. In July 2018, Christine joined the Sullivan lab, where she currently studies the viral diversity and ecology of microbial communities from different soils and permafrost. In 2022, she became a Senior data analyst at OSU’s Microbiome Platform.

Dean Vik, PhD |
Dean joined the Sullivan Lab in Fall 2014 from his undergraduate degree at the University of Hawaii at Manoa. He is very interested in virus-host interactions as they influence microbial evolution and large scale ecosystem functions such as oceanic nutrient cycling. His thesis focus was on archaeovirus biogeography in oxygen minimum zones. Since 2022, he has been developing microbiome workflows in his role as a Senior data analyst at OSU’s Microbiome Platform.

Olivier Zablocki, PhD |
Olivier obtained his PhD in Microbiology in 2016 from the University of Pretoria (South Africa) in Don Cowan’s lab, where he studied the taxonomic and functional diversity of virus communities in hyperarid desert soils (Antarctica and Namibia) through metagenomics. In his first postdoc, he moved to the University of the Western Cape (South Africa) where he looked at virus diversity in a terrestrial hot spring for mining viral thermophilic enzymes with potential biotechnological applications. He also led the development and optimization of a viral tagging/cytometry assay for the isolation of virus-host pairs from environmental samples. In February 2018, Olivier joined the Sullivan lab, where his main research entails terrestrial viromics, which seeks to identify the diversity, roles and impacts of virus communities in shaping soil ecosystem dynamics such as carbon turnover, host mortality and evolution. He’s also involved in cataloging the human gut virome, as well as developing new approaches to analyze viromes with long-read (Nanopore) technology. In 2021, he transitioned to a Grant & Scientific Writer role in the Sullivan Lab and the Center of Microbiome Science at OSU.

Ahmed Zayed, PhD |
Ahmed Zayed joined the Sullivan Lab in Spring 2017 as a PhD student. Before coming to the lab, he finished his master’s degree in Microbiology and Immunology and his undergraduate degree in Pharmaceutical Sciences, both from Cairo University, Egypt. Co-advised by Dr. Virginia Rich at OSU, he completed his PhD in 2019 where he studied microbe-environment interactions in the arctic and sub-arctic terrestrial and aquatic systems. Ahmed is interested in studying complex microbial and viral communities as well as their complex interactions across diverse ecosystems, including the global ocean, soils, and animal-associated ecosystems. By understanding the global and local determinants of community structure and function, he aims at finding solutions to global environmental and health problems. He is currently a Research Scientist in the Sullivan Lab.

Zhiping Zhong photo

Zhiping Zhong, PhD |
Zhiping got his PhD in Microbiology in the Institute of Microbiology, Chinese Academy of Sciences, where he focused on microbial ecology and bacterial taxonomy. He is interested in isolating and identifying bacterial strains, exploring the uncultured microorganisms, and investigating the microbial community structure, function and dynamics in the environment. He joined the Sullivan lab on August 1st 2016 to study microbial and viral ecology in the ice cores from selected depths deposited ~1,000 to ~1,000,000 years ago, which might help provide a window into how microbial life has changed over tens to hundreds of thousands of years. He is currently a postdoctoral researcher at the Byrd Polar and Climate Research Center at the Ohio State University.

Guillermo Dominguez Huerta, PhD |
Guillermo obtained his MSc in Advanced Biotechnology from the International University of Andalusia (Spain) and his PhD in Biology from the University of Malaga (Spain), where he studied the evolution of TYLCD-like begomoviruses following the theory of viral quasispecies. In October 2017 he joined the Sullivan lab, where he studies RNA viral communities from sea water, analyzing their diversity and their ecological implications in the ocean ecosystem. Guillermo is currently a postdoc at the Malaga Oceanographic Centre, Spain.

Former Ph.D Students

Jingjie Du, PhD Student | du.619@buckeyemail.osu.eduJingjie on Twitter
Jingjie joined the Sullivan Lab in Spring 2018. Jingjie received her B.S. degree from Sun Yet-sen University, Guangzhou, China in 2017. Her collegiate research focused on interactions between viruses (ZIKA virus) and the hosts, along with some projects concerning microRNA and cancer. Currently she is looking at whether marine viruses predict carbon flux in Tara GOV.2.0, as well as seeking to understand how viruses and microbes impact recovery from Spinal Cord Injury in mice. She is currently enrolled in a PhD program at Cornell university.

GregoryAnn Gregory,
Ann joined the Sullivan Lab as a technician in August 2010 from her undergraduate degree at Occidental College to learn diverse lab protocols and be exposed to the world of marine viruses. Ann since chose to pursue a PhD, started in August 2012 – her thesis focused on the Population Genomics of 150 cyanophage isolates. She is currently a postdoctoral researcher in the Laboratory of Molecular Bacteriology (Rega Institute) at KU Leuven, Belgium.

Bonnie Hurwitz, Ph.D |
As a PhD student from September 2009 to November 2012, Bonnie applied her extensive informatic and databasing experience to TMPL’s large-scale informatics problems. Her thesis focused broadly on “Pacific Ocean viruses” making use of large, highly contextualized metagenomic datasets from from Scripps Pier, Monterey Bay line67, and LineP, but incorporated significant informatic tool development as well as revealing novel biological insight into the sunlit and dark oceans. She is currently an Assistant Professor in the University of Arizona’s Department of Agricultural and Biosystems Engineering. The Hurwitz Lab

Julio Cesar Ignacio-Espinoza, Ph.D |
Cesar originates from Oaxaca, Mexico and joined the Sullivan Lab in August 2008. He completed a 2 year masters degree in Ecology and Evolutionary Biology, and received his Ph.D. in Molecular & Cellular Biology in December 2014. His research is focused on the ecology and evolution of an abundant ocean viral group, the T4-like viruses. He then moved to the University of Southern California as a postdoctoral researcher. As of summer 2023, he has started a research group as a faculty member at the Keck Graduate Institute (KGI) in Los Angeles.

Funing Tian,  PhD |
Funing joined the Sullivan Lab in Spring 2019 after she received her B.S. degree at Northwest A&F University in China. She used to focus on viral assembly and vaccine development. Currently, she is interested in marine viral manipulation on microbial community and hence the biogeochemical cycling with the application of omics data.


TrublGareth (Gary)
Gary joined the Sullivan Lab as a graduate student in Spring 2014 being co-advised by Dr. Virginia Rich (since July 2013). His thesis work focuses on the role of viruses in a climate-affected peatland across a thawing permafrost gradient in northern Sweden. He examines viral community structure and their contribution to biogeochemical cycling using ecological methods and meta-omics. Gary is now a research scientist at the Lawrence Livermore National Laboratory.

Liu Yunxiao |
Yunxiao joined the Sullivan Lab in Spring 2017 after he graduated from Peking University in China. He’s been working on bacterial responses to osmotic shocks as well as culturing uncultivable bacteria during his undergraduate research. He takes particular interest in how bacteria defend themselves against environmental challenges, including phage infections, and how to utilize their stress responses to develop future therapies.

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