Abstract
Abstract. Thaumarchaeota are amongst the most abundant microorganisms in aquatic environments, however, their metabolism in marine sediments is still debated. Labeling studies in marine sediments have previously been undertaken, but focused on complex organic carbon substrates which Thaumarchaeota have not yet been shown to take up. In this study, we investigated the activity of Thaumarchaeota in sediments by supplying different 13C-labeled substrates which have previously been shown to be incorporated into archaeal cells in water incubations and/or enrichment cultures. We determined the incorporation of 13C-label from bicarbonate, pyruvate, glucose and amino acids into thaumarchaeal intact polar lipid-glycerol dibiphytanyl glycerol tetraethers (IPL-GDGTs) during 4–6 day incubations of marine sediment cores from three sites on the Iceland shelf. Thaumarchaeal intact polar lipids, in particular crenarchaeol, were detected at all stations and concentrations remained constant or decreased slightly upon incubation. No 13C incorporation in any IPL-GDGT was observed at stations 2 (clay-rich sediment) and 3 (organic-rich sediment). In bacterial/eukaryotic IPL-derived fatty acids at station 3, contrastingly, a large uptake of 13C label (up to + 80‰ ) was found. 13C was also respired during the experiment as shown by a substantial increase in the 13C content of the dissolved inorganic carbon. In IPL-GDGTs recovered from the sandy sediments at station 1, however, some enrichment in δ13C (1–4‰ ) was detected after incubation with bicarbonate and pyruvate. The low incorporation rates suggest a low activity of Thaumarchaeota in marine sediments and/or a low turnover rate of thaumarchaeal IPL-GDGTs due to their low degradation rates. Cell numbers and activity of sedimentary Thaumarchaeota based on IPL-GDGT measurements may thus have previously been overestimated.
Highlights
IntroductionThaumarchaeota are ubiquitous microorganisms (Hatzenpichler, 2012 and references cited therein) which have recently been discovered to form a separate phylum, the Thaumarchaeota (Brochier-Armanet et al, 2008; Spang et al, 2010)
Thaumarchaeota are ubiquitous microorganisms (Hatzenpichler, 2012 and references cited therein) which have recently been discovered to form a separate phylum, the Thaumarchaeota (Brochier-Armanet et al, 2008; Spang et al, 2010). They were initially discovered as the Marine Group I Crenarchaeota in the coastal and open ocean (DeLong, 1992; Fuhrman et al, 1992; Karner et al, 2001) where they are abundantly present in the epipelagic zone (e.g. Francis et al, 2005; Beman et al, 2008) and in deep water (Fuhrman and Davis, 1997; Herndl et al, 2005; Agogué et al, 2008) where they can be as abundant as the total bacterial population
Incubations of sediment cores from the Iceland shelf were used in order to determine the metabolism of sedimentary Thaumarchaeota
Summary
Thaumarchaeota are ubiquitous microorganisms (Hatzenpichler, 2012 and references cited therein) which have recently been discovered to form a separate phylum, the Thaumarchaeota (Brochier-Armanet et al, 2008; Spang et al, 2010). It was suggested that 3-hydroxypropionate/4-hydroxybutyrate pathway was used by these microorganisms (Berg et al, 2007), which was supported by genetic analyses of C. symbiosum (Hallam et al, 2006) and N. maritimus (Walker et al, 2010). In these two species, genes involved in heterotrophic metabolisms were detected, which implies their potential for mixotrophy. The uptake of pyruvate into cell material in cultures of a Thaumarchaeote enriched from soil, Nitrososphaera viennensis, was demonstrated (Tourna et al, 2011)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
