Ammonia-oxidizing archaea release a suite of organic compounds potentially fueling prokaryotic heterotrophy in the ocean

Barbara Bayer, Roberta L Hansman, Meriel J Bittner, Beatriz E Noriega-Ortega, Jutta Niggemann, Thorsten Dittmar, Gerhard J Herndl

Ammonia-oxidizing archaea (AOA) constitute a considerable fraction of microbial biomass in the global ocean, comprising 20-40% of the ocean's prokaryotic plankton. However, it remains enigmatic to what extent these chemolithoautotrophic archaea release dissolved organic carbon (DOC). A combination of targeted and untargeted metabolomics was used to characterize the exometabolomes of three model AOA strains of the Nitrosopumilus genus. Our results indicate that marine AOA exude a suite of organic compounds with potentially varying reactivities, dominated by nitrogen-containing compounds. A significant fraction of the released DOM consists of labile compounds, which typically limit prokaryotic heterotrophic activity in open ocean waters, including amino acids, thymidine, and B vitamins. Amino acid release rates corresponded with ammonia oxidation activity and the three Nitrosopumilus strains predominantly released hydrophobic amino acids, potentially as a result of passive diffusion. Despite the low contribution of DOC released by AOA (~0.08-1.05%) to the heterotrophic prokaryotic carbon demand, the release of physiologically relevant metabolites could be crucial for microbes that are auxotrophic for some of these compounds, including members of the globally abundant and ubiquitous SAR11 clade. This article is protected by copyright. All rights reserved.

Functional and Evolutionary Ecology
External organisation(s)
Environment Laboratories Monaco (IAEA-EL, Carl von Ossietzky Universität Oldenburg, Royal Netherlands Institute for Sea Research
Environmental Microbiology
Publication date
Peer reviewed
Austrian Fields of Science 2012
Marine biology
ASJC Scopus subject areas
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