Xinning Zhang (PI)

photo of Professor Zhang

Position: Faculty
Title: Assistant Professor
Office:  M47 Guyot Hall, Washington Rd., Princeton, NJ 08544
Phone: (609) 258-2489
Assistant: Eva Groves (


Areas: Biogeochemistry, Climate

Prof. Zhang is an environmental microbiologist jointly appointed in the Department of Geosciences and the Princeton Environmental Institute. Zhang’s research aims at providing a mechanistic understanding of how microbial metabolism influences biogeochemical cycling and climate in modern and ancient environments. To determine the key parameters explaining microbial activities and their signatures in the rock record, she applies tools from microbial physiology, molecular ecology, and stable isotope geochemistry to research in lab and field settings.

Zhang earned her Ph.D. in environmental science and engineering from the California Institute of Technology and a B.S. in biological and environmental engineering from Cornell University. She joined the faculty in spring 2017.


Shannon Haynes

Shannon Haynes Photo

Position: Lab manager / research specialist 
Office:  M48 Guyot Hall
Phone: 609-258-3962

Shannon is a research specialist and manager of the Zhang Lab with her primary focus being on the optimization of the lab’s stable isotope facilities for biogeochemical studies.

She is currently a Ph.D. student at the University of Missouri. Her Ph.D. research focuses on the relationship between ocean circulation and climate change in the Late Cretaceous using neodymium isotopes (derived from fossilized fish teeth) as a water mass tracer. She earned her M.Sc. in Geology from the University of Missouri. During her seven years in MO, she managed the departments’ Biogeochemistry Isotope Lab and her research largely focused on the use of geochemical proxies, including stable carbon and oxygen isotopes, to make inferences about paleoclimate and paleoceanography. She received her B.S. in Geology from West Virginia University.   


Areas: Stable isotope geochemistry, biogeochemistry, paleoceanography


Romain Darnajoux

Romain Darnajoux image

Position: LSRF Postdoctoral research fellow
Office:  158 Guyot Hall
Phone: 609-258-1052

I started my education in France, where I studied biological and geological science. After a MSc. in chemistry, I traveled to cold French Canada where I obtained my Ph.D. in biogeochemistry, studying the importance of vanadium in boreal cyanolichens. I continued my training during a first postdoc in soil ecology by studying nitrogen acquisition in boreal forest before I started my present position as a postdoctoral fellow in the Geosciences department of Princeton University.

In the Zhang lab, I am using my multidisciplinary background and training to conduct research on the importance of nitrogenases in coastal environment and sediment. I am also continuing my research on alternative nitrogenases in boreal ecosystems with Prs. Lutzoni (Duke University) and Bellenger (Université de Sherbrooke).



Jared Wilmoth

Photo of Jared Wilmoth outside Guyot Hall

Position: Postdoctoral research fellow
Office:  M48 Guyot Hall
Phone: 609-258-
Dr. Jared Wilmoth studies geological chemistry and microbiology using high-resolution chemical and molecular characterization techniques. The major focus of his experimental research is on investigating and understanding how microbial/environmental interfaces regulate greenhouse gas emissions from wetland and peat soils that undergo dynamic redox oscillations. He earned his PhD in Soil Science (biogeochemistry) from the University of Georgia, Athens Georgia, USA and has completed postdoctoral research at Oak Ridge National Laboratory, TN, USA in the Biological and Nanoscale Systems Group, Biosciences Division.

Ashley Maloney

Ashley Maloney on research cruise


Position: Harry Hess Postdoctoral research fellow
Office: M48 Guyot Hall

Phone: 609-258-3962

Dr. Ashley Maloney joined the Zhang lab in spring 2018. She is interested in how microbes and their biomolecules respond to change and developing tools to help characterize microbial metabolism in modern and past environments. She uses microbiology and stable isotope geochemistry in controlled laboratory studies to complement field observations along physical and metabolic gradients. Ashley earned her PhD in Chemical Oceanography from the University of Washington, Seattle Washington, and her undergraduate and Master’s degrees from Stanford University, Stanford California.

Katja Luxem

Position: Graduate student
Office:  158 Guyot Hall
Phone: (609) 258-2612
Katja is a graduate student in the Geosciences department who is studying canonical and alternative nitrogenases in model N fixers and the environment. She received her B.S. from the California Institute of Technology in 2014 and was a Fulbright scholar in 2015-2016.

Eunah Han

Eunah Hann ask a scientist photo
Position:  Graduate student
Title: Ph.D. Student
Office:  M48 Guyot Hall
Phone: 609-258-3962

Eunah is a graduate student in the Zhang Lab.  She is interested in how cell physiology and biochemistry influence stable nitrogen isotope fractionation during biological nitrogen fixation.  She aims to elucidate how and why isotopic fractionations of nitrogenase isozymes vary.  Currently, she is studying how alterations in the composition and structure of amino acids affect isotope fractionation of Azotobacter vinelandii mutants.  Before joining the Zhang lab she was at the POSTECH (BSc & MSc) and GIST (researcher) in South Korea where she studied marine systems including macrofaunal food web structures, sinking flux of organic matter, and bivalve energy budget.

Kelly Van Baalen

Position:  PEI summer  undergrad researcher


Kayla Dobies

Position:  PEI summer undergrad researcher


Previous group members

Carol Chiu

Position: Undergraduate, CBE 2017
Carol graduated with a B.S. in Chemical and Biological Engineering in 2017. Carol's work aimed at understanding the diversity of canonical Mo and alternative nitrogenases in model microbial communities.

Allison Lee

Position: Undergraduate
Allison is an undergrad majoring in Ecology and Evolutionary Biology. During 2016-2017, she studied the mechanisms underlying 15N fractionation in model N fixers, focusing on growth rate and Fe availability. She also doesn't mind accompanying Xinning for a day of field work in the mud!