TY - JOUR T1 - 14C-dead living biomass: evidence for microbial assimilation of ancient organic carbon during shale weathering JF - Science Y1 - 2001 A1 - Petsch, S. T. A1 - Eglington, T. I. A1 - Edwards, K. J. AB - Prokaryotes have been cultured from a modern weathering profile developed on a approximately 365-million-year-old black shale that use macromolecular shale organic matter as their sole organic carbon source. Using natural-abundance carbon-14 analysis of membrane lipids, we show that 74 to 94% of lipid carbon in these cultures derives from assimilation of carbon-14-free organic carbon from the shale. These results reveal that microorganisms enriched from shale weathering profiles are able to use a macromolecular and putatively refractory pool of ancient organic matter. This activity may facilitate the oxidation of sedimentary organic matter to inorganic carbon when sedimentary rocks are exposed by erosion. Thus, microorganisms may play a more active role in the geochemical carbon cycle than previously recognized, with profound implications for controls on the abundance of oxygen and carbon dioxide in Earth's atmosphere over geologic time. VL - 292 IS - 5519 N1 - Petsch, S TEglington, T IEdwards, K JengHistorical ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.2001/04/03 10:00Science. 2001 May 11;292(5519):1127-31. Epub 2001 Mar 29. JO - 14C-dead living biomass: evidence for microbial assimilation of ancient organic carbon during shale weathering ER -