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

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

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.

Organisation(s)
Department of Limnology and Bio-Oceanography
Journal
Environmental Microbiology
ISSN
1462-2912
DOI
https://doi.org/10.1111/1462-2920.14755
Publication date
07-2019
Publication status
E-pub ahead of print
Peer reviewed
Yes
Austrian Fields of Science 2012
106021 Marine biology
ASJC Scopus subject areas
Environmental Science(all)
Portal url
https://ucris.univie.ac.at/portal/en/publications/ammoniaoxidizing-archaea-release-a-suite-of-organic-compounds-potentially-fueling-prokaryotic-heterotrophy-in-the-ocean(3c1b6fc2-9124-4723-8e61-4cdbe56bcc3e).html