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Stephen Giovannoni standing in lab space

Stephen J. Giovannoni

University Distinguished Professor
Department of Microbiology

Stephen J. Giovannoni

University Distinguished Professor
Department of Microbiology


We study how biology interacts with the atmosphere and the oceans to change global patterns in the movement of carbon and other elements. Our experiments begin at sea, but we carry this research into the laboratory, where we work with microbial cells and genome sequences to discover new cell types and new biochemical transformations of matter. Our goals are to understand how these extraordinary cells evolved, how they function, and how planktonic ecosystems will change in response to ocean warming.

Research Interests

  • Ocean Carbon Cycle
  • Marine Microbiology
  • Microbial Genome Evolution

High Throughput Cultivation Laboratory

Dr. Stephen Giovannoni founded Oregon State's HTCL, which pioneered automated methods for isolating and studying the elusive microbes that often dominate natural ecosystems. His research team developed SAR11 cell culture as a model system for studying the oceanic carbon cycle and streamlining, a path to minimal complexity in microbial cell architecture. His research also focuses on the role of SAR202 marine bacteria in ocean carbon sequestration, and biochemical mechanisms of ocean deoxygenation.

Courses taught


Ph.D., University of Oregon, Biology, 1984

M.A., Boston University, Biology, 1978

B.A., University of California, San Diego, Biology, 1974

College strategic research areas

Biomedical Science Marine Science


  • Selected Publications, see more at PubMed
  • Giovannoni, S., F. Chan, E. Davis, C. Deutsch , S. Wolf. 2021. Biochemical Barriers on the Path to Ocean Anoxia? mBIO. DOI:
  • Kivenson, V. and S. J. Giovannoni. 2020. An Expanded Genetic Code Enables Trimethylamine Metabolism in Human Gut Bacteria. mSystems DOI: 10.1128/mSystems. doi: 00413-20
  • Delmont, T.O., E. Kiefl, O. Kilinc, O.C., Esen, I. Uysal, M.S. Rappé, S. Giovannoni and A.M. Eren. 2019. Single-amino acid variants reveal evolutionary processes that shape the biogeography of a global SAR11 subclade. eLife. 10.7554/eLife.46497
  • Saw, J.H.W., T. Nunoura, M. Hirai, Y. Takaki, R. Parsons, M. Michelsen, K. Longnecker, E.B. Kujawinski, R. Stepanauskas, Z. Landry, C.A. Carlson, S.J. Giovannoni. 2019. Pangenomics reveal diversification of enzyme families and niche specialization in globally abundant SAR202 bacteria. mBIO
  • Giovannoni, S.J., Halsey, K.H., Saw, J., Muslin, O., Suffridge, C., Sun, J., Lee, C-P., Moore, E.R., Temperton, B., and Noell, S.E. 2019. A parasitic arsenic cycle that shuttles energy from phytoplankton to heterotrophic bacterioplankton. mBio, DOI:10.1128/MbIO.00246-19.
  • Halsey, K.H., Giovannoni, S., Graus, M., Zhao, Y., Landry, Z., Thrash, J.C. and de Gouw, J. 2017. Biological cycling of volatile organic carbon by phytoplankton and bacterioplankton. Limnol. and Oceanogr. doi:10.1002/Ino.10596.
  • Landry, Z., Swan, B.K., Herndl, G.J., Stepanauskas, R. and Giovannoni, S.J. 2017. SAR202 Genomes from the dark ocean predict pathways for the oxidation of recalcitrant dissolved organic matter. MBio. 8(2):pii e00413-17.