Stanford University
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ESS Seminar, Cajetan Neubauer: New Isotope Tools for Geobiology

When:
Wednesday, Dec 11, 2019 12:30 PM
Where:
Y2E2 111
More Info:
ESS Seminar, Cajetan Neubauer: New Isotope Tools for Geobiology
Audience:
Faculty/Staff, Students
Sponsor:
Department of Earth System Science

Cajetan Neubauer, Ph.D.
Title: New Isotope Tools for Geobiology
Hosts: Emily Cardarelli, Caroline Famiglietti, Marius von Essen, Malory Brown

Over the last 2-3 years, it has become increasingly clear that modern Orbitrap mass spectrometers are fantastic isotope counting machines, quantifying naturally-occurring differences in the abundance of

stable isotopes with sub-permil precision. Because this now allows the measurement of isotopes in intact molecules and sometimes position-specific isotope ratios, recent advances are opening a wide range of

topics in microbiology, ecology, and geology for refined investigation. Currently, we are pursuing two lines of research: In the first, we are quantifying stable isotopes (incl. so-called 'clumped' isotopes) in oxyanions such as nitrate, phosphate, and sulfate. Because oxyanions are important chemical constituents of virtually every environment on Earth, from ocean to groundwater to atmospheric aerosols to biologic organisms, this technical advance has many potential applications. Examples are studies of paleoenvironments or cryptic microbial redox reactions in the ocean. In the second, we investigate the isotopic structure of the amino acid methionine. Because methionine contains sulfur and is costly to produce for cells, it has evolved important roles in microbial food webs. Methionine is also synthesized industrially at million-ton quantities per year and used as a growth promoter in livestock feed. Our estimate shows that about 10% of the methionine in an average person living in the US currently originates from this petrochemical synthesis. The biological implications of this rapidly increasing input of methionine into the human diet deserve more careful consideration.

Caj Neubauer is currently a fellow of the Hanse-Wissenschaftskolleg at Bremen (Germany), where he collaborates with the organic geochemistry group at MARUM and the developers of Orbitrap MS at Thermo Fisher Scientific. Caj has a Ph.D. in structural biology from the MRC Laboratory of Molecular Biology in Cambridge, UK. During his postdoc in the geobiology program at Caltech, he has developed mass spectrometry methods for quantifying stable isotopes. These have been used for example to estimate the in situ growth rate of pathogens in cystic fibrosis lung infections.

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