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Kathryn Fixen

Assistant Professor


Fixen Lab Website

How do bacteria control electron flow inside the cell and how can we tap into this reducing power for biotechnological purposes? In the Fixen lab, we are working to understand intracellular electron flow in the anoxygenic phototroph, Rhodopseudomonas palustris (R. pal). R. pal can use energy from sunlight and reducing power generated from organic compounds such as lignin to make energy-rich compounds like hydrogen and methane using the enzyme nitrogenase. To understand intracellular electron flow in R. pal, we are working to characterize components of electron transfer and understand how the components are regulated by changes in the environment. Ongoing projects in the lab include 1) understanding the role of redox regulation in controlling electron flow in an anaerobe, and 2) the role and regulation of electron carrier proteins in an anoxygenic phototroph. By understanding intracellular electron transfer, we hope to find ways to direct electrons towards producing large amounts of energy-rich, reduced compounds like hydrogen. 

Selected publications

  • K.R. Fixen, S.R. Starkenburg, C.S. Harwood, and R.A. Cattolico. (2016). Draft genomes of 8 bacterial isolates associated with the haptophyte Chrysochromulina tobin. Genome Announc. 4(6). pii: e01162-16.
  • K.R. Fixen, Y. Zheng, D.F. Harris, S. Shaw, Z.Y. Yang, D.R. Dean, L. Seefeldt, and C.S. Harwood. (2016). Light-driven carbon dioxide reduction to methane by nitrogenase in a photosynthetic bacterium. PNAS. 113(36): 10163-7.
  • K.R. Fixen and C.S. Harwood. (2016). A polymorphism in the oxygen-responsive repressor PpsR2 confers a growth advantage to the purple nonsulfur bacterium Rhodopseudomonas palustris under low light. Photosynth Res.129(2):199-204.
  • K.R. Fixen, Y. Oda, and C.S. Harwood. (2015). Clades of photosynthetic bacteria belonging to the genus Rhodopseudomonas show marked diversity in light-harvesting antenna complex gene composition and expression. mSystems. 1(1): e00006-15.
  • K.R. Fixen, A.W. Baker, E.A. Stojkovic, J.T. Beatty, C.S. Harwood. (2014). Apo-bacteriophytochromes modulate bacterial photosynthesis in response to low light. PNAS. 111(2): E237-44.

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