Zehr Laboratory

Research in our laboratory group focuses on how microorganisms control the availability of nitrogen, a critical element in all life as we know it. Nitrogen, a major plant nutrient, is transformed from one form to another by microorganisms, and moves between habitats. A large reservoir of nitrogen on Earth resides in the air we breath: 80% of the atmosphere is nitrogen gas. Nitrogen gas, or dinitrogen (2 nitrogen atoms triple bonded together) is unavailable to most organisms, in particular the eukaryotic plants and animals. Many diverse prokaryotic microorganisms have the ability to fix nitrogen from the atmosphere into a biologically available form. Biological nitrogen fixation is catalyzed by an enzyme, called nitrogenase. Since most of the microorganisms in the natural environment have yet to be cultivated, we study the microorganisms in the environment that fix nitrogen by looking for the genes and proteins involved in nitrogen fixation.


A.M. Cabello, K.A. Turk‐Kubo, K. Hayashi, L. Jacobs, R.M. Kudela & J.P. Zehr (2020) Journal of Phycology.

M.M. Mills, K.A. Turk-Kubo, G.L. van Dijken, B.A. Henke, K. Harding, S.T. Wilson, KR. Arrigo & J.P. Zehr (2020) ISME J

M.R. Gradoville, H. Farnelid, A.E. White, K.A. Turk‐Kubo, B. Stewart, F. Ribalet, S. Ferrón, P. Pinedo‐Gonzalez, E.V. Armbrust, D.M. Karl, S. John & J.P. Zehr (2020) Limnology and Oceanography.

F.M. Cornejo‐Castillo & J.P. Zehr (2019) PNAS.

K. Harding, K.A. Turk-Kubo, R.E. Sipler, M.M. Mills, D.A. Bronk, J.P. Zehr (2018) PNAS.

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Eddy Exploration & Ecosystem Dynamics
North Pacific Subtropical Gyre (NPSG)
Schmidt Ocean Institute
R/V Falkor, March-April 2018

Postdocs Rosie Gradoville and Ana Maria Cabello joined researchers from SCOPE and MBARI to on a research cruise focused on understanding how meso-scale processes (eddies) influence micro-scale processes (diazotroph activity). 

Check out the cruise blog here

Coastal California/Baja Mexico, R/V Sprout, October 2017

Researchers from UCSC and Stanford recently led an expedition to study the activity of UCYN-A in a coastal shelf ecosystem, in collaboration with researchers from VIMS and UABC. 

Our research is supported by the Simons Foundation, National Science Foundation (NSF), the Gordon and Betty Moore Foundation (GBMF), and Co-funded by the Horizon 2020 Framework Programme of the European Union.

Ocean Sciences Department

1156 High Street

University of California, Santa Cruz, CA 95064

© 2015 by the Zehr Laboratory