title: Inefficient microbial production of refractory dissolved organic matter in the ocean.
abstract: Dissolved organic matter (DOM) in the oceans constitutes a major carbon pool involved in global biogeochemical cycles. More than 96% of the marine DOM resists microbial degradation for thousands of years. The composition of this refractory DOM (RDOM) exhibits a molecular signature ubiquitously detected in the deep oceans. Surprisingly efficient microbial transformation of labile into stable forms of DOM has been shown previously, implying that microorganisms apparently produce far more RDOM than needed to sustain the global pool. Here we show, by assessing the microbial formation and transformation of DOM in unprecedented molecular detail for 3 years, that most of the microbial DOM is different from RDOM in the ocean. Only <0.4% of the net community production is channelled into a form of DOM that is undistinguishable from oceanic RDOM. Our study provides a molecular background for global models on the production, turnover and accumulation of marine DOM.
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University, Oldenburg 26129, Germany.
authors.forename: Helena
authors.initials: H
authors.lastname: Osterholz
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University, Oldenburg 26129, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Niggemann
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University, Oldenburg 26129, Germany.
authors.forename: Helge-Ansgar
authors.initials: HA
authors.lastname: Giebel
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University, Oldenburg 26129, Germany.
authors.forename: Meinhard
authors.initials: M
authors.lastname: Simon
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University, Oldenburg 26129, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Dittmar
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D009930:Organic Chemicals / Q000378:metabolism*; D010839:Phytoplankton / Q000378:metabolism*
chemical_list: D009930:Organic Chemicals