Ann Pearson, Ph.D.

Applications of analytical chemistry, isotope geochemistry, and molecular biology to biochemical oceanography


Illuminating the links between microbial ecosystem structure and function.

Ann Pearson, Ph.D.

Research Description

The goal of my work is to illuminate the links between microbial ecosystem structure and function. My lab uses isotope-enabled geochemical methods often applied to geochemical investigations, but we apply these methods to microbial molecular systems. We examine carbon, nitrogen, sulfur, and oxygen cycling by measuring the stable isotope distributions of these elements in proteins, lipids, pigments, and nucleic acids – using the results as “fingerprinting” techniques to understand resource utilization and sharing in complex natural environments.

Our specific MMI projects include (A) the construction of a bioreactor to measure carbon isotopes during microbial degradation of complex organic matter; (B) examining the extent (or lack) of trophic structure in mixed microbial communities using carbon and nitrogen isotopes; and (C) a variety of investigations into the role and function of Archaea in the marine environment. Ultimately we aim to determine if (i) the molecular structure of substrates or (ii) the type of energy & nutrient environment is more important to establishing and maintaining microbial community structure.

Research Impact

The ability to understand marine ecosystems of the past, present, and future depends on our ability to understand the biochemical complexity found in nature and its effects on global elemental cycles. Whether we are studying microbial pathways of carbon fixation, lipid distributions in marine sediments, or the oxygen requirements of individual enzymes, our goal is to understand how and why microorganisms leave particular chemical signals in the geologic record. This informs us about the roles that microbial communities play in shaping Earth’s environment and allows us to interpret across a wide variety of time-scales, including into the geologic past.


related links

Marine Microbiology Initiative Science Harvard University, Office of Sponsored Programs Back


B.A.: Chemistry, Oberlin College, Oberlin, Ohio, 1992.

Ph.D.: Marine Chemistry and Geochemistry, MIT/WHOI Joint Program in Oceanography, 2000.


Kavli Fellow, National Academy of Sciences, 2013.

Gordon and Betty Moore Foundation Investigator, 2013-2018.

Radcliffe Institute Fellow, 2009-2010.

David and Lucille Packard Foundation Fellowship for Science and Engineering, 2004-2009.

C. G. Rossby Award for Best Dissertation in the Program in Atmospheres, Oceans, and Climate;

Department of Earth, Atmospheric, and Planetary Science; MIT, 2000.

EPA STAR Graduate Student Fellowship, 1997-2000.

Geological Society of America, Organic Geochemistry Division, Most Outstanding Paper, 1997.

Ida M. Green Graduate Student Fellowship, MIT, 1994-1995.

Harry Holmes Prize in Chemistry, Oberlin College, 1992.


Bovee RJ, Pearson A (2014) Strong influence of the littoral zone on sedimentary lipid biomarkers in a

meromictic lake. Geobiology 12, 529-541.

Schouten S, Hopmans EC, Rosell-Melé A, Pearson A, et al. (69 authors) (2013) An interlaboratory study

of TEX86 and BIT analysis of sediments, extracts and standard mixtures. Geochem. Geophys.

Geosyst. 14, 5263-5285.

Close HG, Shah SR, Ingalls AE, Diefendorf A, Brodie EL, Hansman RL, Aluwihare LI, Freeman KH,

Pearson A (2013) Export of submicron particular organic matter to the mesopelagic of an oligotrophic

gyre. Proceedings of the National Academy of Sciences USA 110, 12565-12570.

Pearson A (2013) Lipidomics for geochemistry. Treatise on Geochemistry (2nd Edition) 12, 291-336;

Eds. P. G. Falkowski and K. H. Freeman, Elsevier London.

Pearson A, Ingalls AE (2013) Assessing the utility of archaeal lipids as environmental proxies. Annual

Reviews of Earth and Planetary Sciences 41, 359-384.

Klepac-Ceraj V, Hayes CA, Gilhooly W, Lyons TR, Kolter R, Pearson A (2012) Microbial diversity in

extreme euxinia: Mahoney Lake, Canada. Geobiology 10, 223-235.

Higgins MB, Robinson RS, Carter SJ, Husson J, Pearson A (2012) Dominant eukaryotic export

production during ocean anoxic events reflects the importance of recycled NH4+. Proceedings of the National Academy of Sciences USA 109, 2269-2274.

Higgins MB, Robinson RS, Carter SJ, Husson J, Pearson A (2012) Dominant eukaryotic export

production during ocean anoxic events reflects the importance of recycled NH4+. Proceedings of the

National Academy of Sciences USA 109, 2269-2274.

Jones DS, Albrecht HL, Dawson KS, Schaperdoth I, Freeman KH, Pi Y, Pearson A, Macalady JL (2012)

Community genomic analysis of an extremely acidophilic sulfur-oxidizing biofilm. ISME Journal 6,


Close HG, Bovee RJ, Pearson A (2011) Inverse carbon isotope patterns of lipids and kerogen record

heterogeneous primary biomass Geobiology 9, 250-265.

Bradley AS, Pearson A, Saenz JP, Marx CJ (2010) Adenosylhopane: the first step in biosynthesis of

hopanoid side chains. Org Geochem 41, 1075-1081.

Higgins MB, Robinson RS, Carter SJ, & Pearson A (2010) Evidence from chlorin nitrogen isotopes for

alternating nutrient regimes in the Eastern Mediterranean Sea. Earth Planet. Sci. Lett. 290, 102-107.

Pearson A (2010) Pathways of carbon assimilation and their impact on organic matter values of 13C. In:

Handbook of Hydrocarbon Microbiology: Microbial interactions with hydrocarbons, oils, fats, and

related hydrophobic substrates and products. Ed. K. Timmis, Springer-Verlag Berlin: DOI

10.1007/978-3-540-77587-4_9; pp. 143-156.

Brocks JJ, Bosak T, Pearson A (2009) Oligoprenyl-curcumanes and other new aromatic isoprenoids from

the 1.64 billion years old Barney Creek Formation. Org Geochem 40, 795-801.

Johnston DA, Wolfe-Simon FL, Pearson A, & Knoll AH (2009) Anoxygenic photosynthesis modulated

Proterozoic oxygen and sustained Earth’s middle age. Proceedings of the National Academy of

Sciences USA 106, 16925-16929.

Mikucki JA, Pearson A, Turchyn AV, Johnston DA, Anbar AD, Priscu J, Schrag D, Farquhar J, & Lee

PD (2009) A contemporary microbially-maintained ferrous subglacial ‘ocean’. Science 324, 397-400.

Hansman RL, Griffin S, Watson JT, Druffel ERM, Ingalls AE, Pearson A, & Aluwihare LI (2009) The

radiocarbon signature of microbial organisms in the mesopelagic ocean. Proceedings of the National

Academy of Sciences USA 106, 6513-6518.

Schouten S, Hopmans E, Van Der Meer J, Mets A, Bard E, Bianchi T, Diefendorf A, Escala M, Freeman

KH, Huguet C, Ingalls A, Ménot-Combes G, Nederbracht AJ, Oba M, Pearson A, Pearson E, Rosell-

Liu Z, Pagani M, Zinniker D, DeConto R, Huber M, Brinkhuis H, Shah S, Leckie M, & Pearson A (2009)

Global cooling during the Eocene-Oligocene climate transition. Science 323, 1187-1190.

Affiliated Investigators