MISSION

Microbes catalyze a huge diversity of biochemical reactions that are important to human health and essential to the persistence of life on this planet. But no one microbe can do it all. Our lab is interested in how limitations placed on cells by physics, chemistry, and biology influence the biochemical scope of what microbes can do, how fast they can do it, and how these limitations affect the organisms around them.

Many of these important microbial reactions involve nitrogen. We specifically study denitrification, the stepwise respiration of nitrate to dinitrogen gas, which plays a central role in Pseudomonas aeruginosa pathogenesis, gut dysbiosis, and environmental nitrogen cycling. The denitrification pathway is made up of four sequential reactions, but most organisms specialize in only some of them. This is puzzling, given that running the complete pathway extracts more energy per nitrate. We think an explanation lies in the tradeoffs cells face when balancing competing demands given finite resources (i.e., proteome space, reducing equivalents, carbon, and the capacity to respond to stress). Our goal is to uncover the fundamental basis for tradeoffs in denitrification, the costs and benefits of specializing, and the consequences for microbial communities and hosts.

We focus experimentally on pseudomonads, which are genetically tractable and exhibit enormous natural diversity in which denitrification steps they can do. We take a systems biology perspective to connect intracellular tradeoffs to growth, metabolic flux, and the ecology of denitrifying communities.

NEWS

• March 2026: We welcome Arthur Franklin who will join the lab as a Microbiology PhD student. Arthur will work on microbial interactions in biofilms.
• Jan 2026: We are super excited to welcome Andrew Schwieters to the lab as a postdoctoral researcher. Andrew will develop new synthetic biology tools for studying bacterial denitrification.
• Aug 2025: Big congrats to Bryce Guidry for successfully completing his PhD candidacy examinations in the Biophysics Graduate Program.
• May 2025: We welcome summer REU student Emily Yoon to the lab. Emily is a rising junior at Williams College, and will be working on enrichhing denitrifying biofilms.
• February 2025: We are thrilled to have Dominic Cipiti joining the lab as a Microbiology PhD student. He will take a resource-allocation perspective to the study of denitrification physiology.
• January 2025: We welcome Bryce Guidry and Anja Steinert to the lab. Bryce joins as a PhD student through the Biophysics Graduate Program and will be working on single-cell approaches for studying bacteria. Anja will be taking over as lab manager.
• July 2024: Our paper on how interactions shape denitrifying communities in the soil microbiome is now out in Nature Microbiology.

PEOPLE

Karna Gowda, PhD [CV]

Principal Investigator
Department of Microbiology
Biophysics Graduate Program
The Ohio State University

Dominic Cipiti

PhD Student, Microbiology
BS in Biology, Baldwin Wallace University

Arthur Franklin

PhD Student, Microbiology
BS in Biology, The Ohio State University

Bryce Guidry

PhD Candidate, Biophysics
BS in Biophysics, Emory University

Anja Howard

Lab Manager
BS in Biology, The Ohio State University

Andrew Schwieters

Postdoctoral Researcher
BS/BA in Biology and Chemistry, University of Minnesota, Morris
PhD in Microbiology, The Ohio State University

Aayushi Shah

High School Intern

Kuromatsu

Dog

Alumni

• Ava Galek, Undergraduate Lab Assistant (2025-2026)
• Emily Yoon (Williams College), SROP Researcher (2025)
• Molly Easton, Undergraduate Lab Assistant (2024-2025)
• Aouss Azzouz (Earlham College→UPenn Medical School), SROP Researcher (2024)

PUBLICATIONS

2025

Urvoy, M., Howard-Varona, C., Owusu-Ansah, C., Stai, A. J., Bouranis, J. A., Burris, M., Solonenko, N., Hettich, R. L., Holmfeldt, K., Tfaily, M., Gowda, K., Sullivan & M. B. (2025). Phage resistance mutations in a marine bacterium impact biogeochemically relevant cellular processes. Nature Microbiology, 11, 195–210. doi: 10.1038/s41564-025-02202-5

2024

Crocker, K., Lee, K. K., Chakraverti-Wuerthwein, M., Li, Z., Tikhonov, M., Mani, M., Gowda, K., & Kuehn, S. (2024). Environmentally dependent interactions shape patterns in gene content across natural microbiomes. Nature Microbiology, 9(8), 2022–2037. doi: 10.1038/s41564-024-01752-4

2023

Skwara, A., Gowda, K., Yousef, M., Diaz-Colunga, J., Raman, A. S., Sanchez, A., Tikhonov, M., & Kuehn, S. (2023). Statistically learning the functional landscape of microbial communities. Nature Ecology & Evolution, 7(11), 1823–1833. doi: 10.1038/s41559-023-02197-4

Diaz-Colunga, J., Skwara, A., Gowda, K., Diaz-Uriarte, R., Tikhonov, M., Bajic, D., & Sanchez, A. (2023). Global epistasis on fitness landscapes. Philosophical Transactions of the Royal Society B, 378(1877), 1–20. doi: 10.1098/rstb.2022.0053

2022

Gowda, K., & Kuehn, S. (2022). Microbial biofilms: An ecological tale of Jekyll and Hyde. Current Biology, 32(24), R1349–R1351. doi: 10.1016/j.cub.2022.10.068

Gowda, K., Ping, D., Mani, M., & Kuehn, S. (2022). Genomic structure predicts metabolite dynamics in microbial communities. Cell, 185(3), 530-546.e25. doi: 10.1016/j.cell.2021.12.036

Gopalakrishnappa, C., Gowda, K., Prabhakara, K. H., & Kuehn, S. (2022). An ensemble approach to the structure-function problem in microbial communities. iScience, 25(2), 103761. doi: 10.1016/j.isci.2022.103761

2020

Fraebel, D. T., Gowda, K., Mani, M., & Kuehn, S. (2020). Evolution of Generalists by Phenotypic Plasticity. iScience, 23(11), 1–22. doi: 10.1016/j.isci.2020.101678

PhD

Gandhi, P., Werner, L., Iams, S., Gowda, K., & Silber, M. (2018). A topographic mechanism for arcing of dryland vegetation bands. Journal of the Royal Society Interface, 15(147). doi: 10.1098/rsif.2018.0508

Gowda, K., Iams, S., & Silber, M. (2018). Signatures of human impact on self-organized vegetation in the Horn of Africa. Scientific Reports, 8(1), 1–8. doi: 10.1038/s41598-018-22075-5

Gowda, K., Chen, Y., Iams, S., & Silber, M. (2016). Assessing the robustness of spatial pattern sequences in a dryland vegetation model. Proceedings of the Royal Society A, 472(2187). doi: 10.1098/rspa.2015.0893

Gowda, K., & Kuehn, C. (2015). Early-warning signs for pattern-formation in stochastic partial differential equations. Communications in Nonlinear Science and Numerical Simulation, 22(1–3), 55–69. doi: 10.1016/j.cnsns.2014.09.019

Gowda, K., Riecke, H., & Silber, M. (2014). Transitions between patterned states in vegetation models for semiarid ecosystems. Physical Review E, 89(2), 1–8. doi: 10.1103/PhysRevE.89.022701