Group [internal]



Group members.

Individuals interested in undergraduate, graduate, or postdoc research opportunities in the Fischer Group at Caltech are urged to send a brief statement of background and interest. [recruitment]

Woodward W. Fischer [principal investigator]

Professor of Geobiology in Geological and Planetary Sciences. PhD Harvard University. BA Colorado College. I'm often called by my nickname, Woody. My research generally falls in the discipline of Geobiology—combining techniques from field geology, analytical chemistry, and biology— to understand and explore the relationships between of life and Earth surface environments through diverse and fundamental transitions in Earth history. Read a brief interview with Woody.

Preston Cosslett Kemeny

Graduate Student (Hertz NDSEG). AB Princeton University. I am interested in the mutual interactions between the evolution of life and global biogeochemical cycles, as recorded in the stable isotope ratios of natural materials in the geologic record. My research combines fieldwork, experimental measurements, thermodynamic calculations, and numerical models to understand the large-scale geochemical and geobiological processes that generate Earth’s climate, both now and in the past. My current projects include using sulfur isotope ratios to constrain sulfur cycling and fluxes of organic matter in river catchments and using nitrogen isotope ratios to model glacial nutrient dynamics in the Southern Ocean. I am also interested in the physical chemistry underlying isotopic variation, particularly with respect to molecules with multiple isotopic substitutions or which fail to obey canonical mass-law relationships. When outside the lab, I like to hike and talk about science.

Usha Lingappa

Graduate Student (NSF GRFP). BA Hampshire College. I'm broadly interested in manganese, phototrophy, and the biogenesis of proteins critically important for biogeochemical processes in the environment. With Woody Fischer, I'm studying Mn oxidation by Cyanobacteria. This work is both to explore a possible evolutionary stepping stone in the origin of oxygenic photosynthesis based on Mn phototrophy, and also to characterize a previously unappreciated branch of environmental Mn cycling.

John S. Magyar

Research Scientist. PhD, Northwestern University. AB, Dartmouth College. My current work in the Fischer group is focused on biological manganese oxidation related to the evolution of photosystem II. Previously, I was a chemistry professor at Barnard College, Columbia University, where I continue to advise undergraduate research students. We are exploring molecular mechanisms of cold adaptation, specifically in the hydrocarbonoclastic, psychrophilic bacterium Colwellia psychrerythraea. We are also investigating the molecular details of trace metal uptake and homeostasis in environmentally important microorganisms, such as marine phytoplankton and methanogenic archaea. Before Barnard, I was a postdoctoral scholar in chemistry at Caltech (with Harry B. Gray), where I studied electron-transfer kinetics and protein dynamics in cytochrome c. My doctoral research, with Hilary Arnold Godwin, provided important insights into the molecular mechanisms of lead(II) poisoning.

Kyle Metcalfe

Graduate Student (NSF GRFP). BA Pomona College. I’m interested in the microbe-mineral interface and studying the dynamics of biomineralization by microbes in both culture and the environment. Working with Victoria Orphan and Woody Fischer, I’m working on a project focusing on silicate biomineralization of anaerobic methane-oxidizing (AOM) microbial consortia. Microbial silicate biomineralization in non-hydrothermal environments is poorly recognized, but may provide insight into biogeochemical cycles and the physiology and ecology of microbial aggregates and communities. I’m currently characterizing the mineralogy and architecture of silicate shells enveloping AOM consortia with X-ray spectroscopy to understand the function of these biomaterials. Additionally, I have worked with Woody to unravel some of the history preserved in manganese-rich sedimentary rocks.

Danielle Monteverde (Potocek)

GPS Geobiology Postdoctoral Scholar. PhD University of Southern California. BS Bucknell University. I am interested in the role coenzymes play in modern and ancient environments. I have a particular interest in flavins, which can aide microbes in extracellular electron transfer to insoluble iron and manganese oxides. My research seeks to understand their cycling and distribution in modern environments. I am also interested in exploring the role certain metals and metallocoenzymes (e.g., manganese and cobalamin) have played in early biological innovations such as phototrophy and methyl transfers. My research involves the development of methods utilizing solid phase extraction and HPLC-MS to measure trace concentrations (pM-nM) of coenzymes in the environment, paired alongside microbial and geochemical sampling techniques. In my spare time you can find me at the beach playing fetch with my dog, Bo.

Christopher Spalding

Graduate Student (NESSF). BA/MSci University of Cambridge. An Astrophysicist by training and practice, I'm working with Konstantin Batygin on the dynamics of planetary systems with a focus on excitation of spin-orbit misalignments in close-in planetary systems. But I'm also leading a somewhat double life as a 'geobiologist' in the Fischer Group. My interests here generally lie in deciphering the influences that have shaped the course of evolution using mathematical techniques. In particular, I have developed an analytical model that quantifies the energetic costs to an organism of building a calcium carbonate shell, and how these costs change as a function of seawater chemistry. The goal is to determine why some groups have been more susceptible than others to extinction during past events of ocean acidification, such as the Permian-Triassic Mass Extinction, and provide some fresh insights into extinction risk for modern fisheries associated with ocean acidification.

Joan Selverstone Valentine

Visiting Associate Caltech. Distinguished Research Professor UCLA. PhD Princeton University. AB Smith College. I am a biological inorganic chemist and biochemist; much of my work focused on the role of transition metals, metalloenzymes, and oxidative stress in human health. I have had a long fascination with the redox history of our planet, and am working with the Fischer Group to better understand the mechanisms that allowed life to tolerate, and ultimately thrive in the presence of dioxygen. View a 30 min. interview with Joan.

Xingchen (Tony) Wang

Simons Foundation Postdoctoral Fellow on the Origins of Life. PhD Princeton University. BS, Nanjing University. My research is focused on the cycling of nitrogen in the modern and past oceans. As a part of this effort, I develop and apply new methods to analyze the isotopic composition of nitrogen in fossils (e.g. corals and stromatolites) as well as in modern marine environments (e.g. reefs). I also employ calculations from simple mathematical models to quantitatively interpret these data. At Caltech I am working with Alex Sessions, Jess Adkins, and Woody Fischer on ocean biogeochemical changes over a broad range of timescales throughout the Earth history, ranging from the Archean to the Quaternary intervals.


Kristin Bergmann (former graduate student, now faculty at MIT)

Renata Cummins (former graduate student, now at Risk Management Solutions)

Seth Finnegan (former postdoc, now faculty at UC Berkeley, Dept. of Integrative Biology)

Aya Gerpheide (former undergraduate, Oxy, now SCI-Arc, Los Angeles, CA)

Itay Halevy (former postdoc, now at Weizmann Institute, Dept. of Environmental Sciences)

James Hemp (former postdoc, now at University of Utah, School of Medicine)

Jena Johnson (former graduate student, Clauser Prize winner, now faculty at Michigan)

Carina Lee (former staff, PhD at UCR, now postdoc at UC Berkeley)

Ariel Liu (former high school student, Troy, now at Stanford University)

Hanna Liu (former undergraduate, now at UCI School of Medicine)

Allison Maker (former undergraduate, now at University of Washington, Dept. of Biochemistry)

Noah Planavsky (former postdoc, now at Yale, Dept. of Geology & Geophysics)

Nikhita Poole (former high school student, now at Caltech)

Chris Reinhard (former postdoc, now at Georgia Tech Dept. of Earth and Atmospheric Sciences)

Sarah Slotznick (former graduate student, now Miller Postdoctoral Fellow at Berkeley)

Vlada Stamenkovic (former SCOL postdoc, now JPL scientist)

Kevin Sutherland (former undergraduate, now at MIT/WHOI)

Mark Torres (former Texaco/AGEP postdoc, now faculty at Rice)

Elizabeth Trembath-Reichert (former graduate student, now NASA NPP at WHOI)

Lizzy Trower (former postdoc, now faculty at CU Boulder)

Lewis Ward (former graduate student, now Agouron Postdoctoral Fellow at Harvard)

Jon Wilson (former postdoc, now at Haverford College, Dept. of Biology)

Rebecca Zentmyer (former staff)

Past SURF and MURF students.

Allison Maker (Caltech '15), Juliet Su (Caltech '16), Aya Gerpheide (Oxy '14), Hanna Liu (Caltech '11), Haley Barnes (Caltech '12).