Carbon limitation leads to thermodynamic regulation of aerobic metabolism

Garayburu-Caruso, V.; Stegen, J.; Song, H.-S.; Renteria, L.; Wells, J.; Garcia, W.; Resch, C. T.; Goldman, A.; Chu, R.; Toyoda, J.; Graham, E. B.

doi:10.1101/2020.01.15.905331

bioRxiv · 10.1101/2020.01.15.905331

Carbon limitation leads to thermodynamic regulation of aerobic metabolism

Garayburu-Caruso, V.·Stegen, J.·Song, H.-S.·Renteria, L.·Wells, J.·Garcia, W.·Resch, C. T.·Goldman, A.·Chu, R.·Toyoda, J.·Graham, E. B.

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Abstract

Organic matter (OM) metabolism in freshwater ecosystems is a critical source of uncertainty in global biogeochemical cycles, yet aquatic OM cycling remains poorly understood. Here, we present the first work to explicitly test OM thermodynamics as a key regulator of aerobic respiration, challenging long-held beliefs that organic carbon and oxygen concentrations are the primary determinants of respiration rates. We pair controlled microcosm experiments with ultrahigh-resolution OM characterization to demonstrate a clear relationship between OM thermodynamic favorability and aerobic respiration under carbon limitation. We also demonstrate a shift in the regulation of aerobic respiration from OM thermodynamics to nitrogen content when carbon is in excess, highlighting a central role for OM thermodynamics in aquatic biogeochemical cycling particularly in carbon-limited ecosystems. Our work therefore illuminates a structural gap in aquatic biogeochemical models and presents a new paradigm in which OM thermodynamics and nitrogen content interactively govern aerobic respiration.

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Garayburu-Caruso, V., Stegen, J., Song, H.-S., Renteria, L., Wells, J., Garcia, W., Resch, C. T., Goldman, A., Chu, R., Toyoda, J., Graham, E. B.. 2020-01-15. Carbon limitation leads to thermodynamic regulation of aerobic metabolism. https://doi.org/10.1101/2020.01.15.905331

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