| Autor: |
Kitzinger K; Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany. kkitzing@mpi-bremen.de.; Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, 1090, Vienna, Austria. kkitzing@mpi-bremen.de., Marchant HK; Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany. hmarchan@mpi-bremen.de., Bristow LA; Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany.; Department of Biology, University of Southern Denmark, 5230, Odense, Denmark., Herbold CW; Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, 1090, Vienna, Austria., Padilla CC; School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332-0230, USA., Kidane AT; Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany., Littmann S; Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany., Daims H; Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, 1090, Vienna, Austria.; The Comammox Research Platform, University of Vienna, 1090, Vienna, Austria., Pjevac P; Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, 1090, Vienna, Austria.; Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, 1090, Vienna, Austria., Stewart FJ; School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332-0230, USA., Wagner M; Centre for Microbiology and Environmental Systems Science, Division of Microbial Ecology, University of Vienna, 1090, Vienna, Austria.; The Comammox Research Platform, University of Vienna, 1090, Vienna, Austria.; Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, 1090, Vienna, Austria.; Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, 9220, Aalborg, Denmark., Kuypers MMM; Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany. |
| Abstrakt: |
Nitrification, the oxidation of ammonia via nitrite to nitrate, is a key process in marine nitrogen (N) cycling. Although oceanic ammonia and nitrite oxidation are balanced, ammonia-oxidizing archaea (AOA) vastly outnumber the main nitrite oxidizers, the bacterial Nitrospinae. The ecophysiological reasons for this discrepancy in abundance are unclear. Here, we compare substrate utilization and growth of Nitrospinae to AOA in the Gulf of Mexico. Based on our results, more than half of the Nitrospinae cellular N-demand is met by the organic-N compounds urea and cyanate, while AOA mainly assimilate ammonium. Nitrospinae have, under in situ conditions, around four-times higher biomass yield and five-times higher growth rates than AOA, despite their ten-fold lower abundance. Our combined results indicate that differences in mortality between Nitrospinae and AOA, rather than thermodynamics, biomass yield and cell size, determine the abundances of these main marine nitrifiers. Furthermore, there is no need to invoke yet undiscovered, abundant nitrite oxidizers to explain nitrification rates in the ocean. |
