title: Social dynamics within decomposer communities lead to nitrogen retention and organic matter build-up in soils.
abstract: The chemical structure of organic matter has been shown to be only marginally important for its decomposability by microorganisms. The question of why organic matter does accumulate in the face of powerful microbial degraders is thus key for understanding terrestrial carbon and nitrogen cycling. Here we demonstrate, based on an individual-based microbial community model, that social dynamics among microbes producing extracellular enzymes ('decomposers') and microbes exploiting the catalytic activities of others ('cheaters') regulate organic matter turnover. We show that the presence of cheaters increases nitrogen retention and organic matter build-up by downregulating the ratio of extracellular enzymes to total microbial biomass, allowing nitrogen-rich microbial necromass to accumulate. Moreover, increasing catalytic efficiencies of enzymes are outbalanced by a strong negative feedback on enzyme producers, leading to less enzymes being produced at the community level. Our results thus reveal a possible control mechanism that may buffer soil CO2 emissions in a future climate.
authors.affiliation: Evolution and Ecology Program, International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, A-2361 Laxenburg, Austria.|Department of Microbiology and Ecosystem Science, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Christina
authors.initials: C
authors.lastname: Kaiser
authors.affiliation: Ecosystem Services and Management Program, International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, A-2361 Laxenburg, Austria.|Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
authors.forename: Oskar
authors.identifier: http://orcid.org/0000-0002-0376-4140
authors.initials: O
authors.lastname: Franklin
authors.affiliation: Department of Microbiology and Ecosystem Science, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Richter
authors.affiliation: Evolution and Ecology Program, International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, A-2361 Laxenburg, Austria.
authors.forename: Ulf
authors.initials: U
authors.lastname: Dieckmann
mesh_terms: D001419:Bacteria / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D001426:Bacterial Proteins; D012987:Soil; D002244:Carbon; D009584:Nitrogen