Abundance of planktonic thraustochytrids and bacteria and the concentration of particulate ATP in the Greenland and Norwegian Seas

Surface water samples were collected at 15 sites in the Greenland and Norwegian Seas, and total planktonic thraustochytrids and bacteria were directly counted by epifluorescence microscopy. Particulate (>0.2 μm) adenosine 5\u27-triphosphate (ATP) was also determined by bioluminescence photometry. Abundance of planktonic thraustochytrids varied from below the detection limit (<8.1×102 l^(-1)) to 2.3×105 l^(-1) with an overall average of 3.1×104 l^(-1). Abundance of bacterioplankton ranged from 2.2×107 l^(-1) at the northernmost site to 6.0×108 l^(-1) at the southernmost site with an overall average of 2.1×108 l^(-1). Particulate ATP concentration ranged from 79 pmol to 676 pmol at the mid-transect (68°N) and southernmost (62°N) sites, respectively, with an overall average of 222 pmol. The measured ATP concentrations were too low to account for the abundance of thraustochytrids and bacteria estimated from total counts and carbon-per-cell factors. However, particulate ATP was correlated with the abundance of bacterioplankton, but not that of planktonic thraustochytrids. These differing relationships suggest different physiological and biochemical strategies of starvation survival and differing substrate availability in the Arctic and sub-Arctic surface waters

Dissimilatory sulfate reduction in the archaeon ‘Candidatus Vulcanisaeta moutnovskia’ sheds light on the evolution of sulfur metabolism

Dissimilatory sulfate reduction (DSR)—an important reaction in the biogeochemical sulfur cycle—has been dated to the Palaeoarchaean using geological evidence, but its evolutionary history is poorly understood. Several lineages of bacteria carry out DSR, but in archaea only Archaeoglobus, which acquired DSR genes from bacteria, has been proven to catalyse this reaction. We investigated substantial rates of sulfate reduction in acidic hyperthermal terrestrial springs of the Kamchatka Peninsula and attributed DSR in this environment to Crenarchaeota in the Vulcanisaeta genus. Community profiling, coupled with radioisotope and growth experiments and proteomics, confirmed DSR by ‘Candidatus Vulcanisaeta moutnovskia’, which has all of the required genes. Other cultivated Thermoproteaceae were briefly reported to use sulfate for respiration but we were unable to detect DSR in these isolates. Phylogenetic studies suggest that DSR is rare in archaea and that it originated in Vulcanisaeta, independent of Archaeoglobus, by separate acquisition of qmoABC genes phylogenetically related to bacterial hdrA genes.This work was supported by the Russian Science Foundation (grant number 17-74-30025) and in part by the grant from the Russian Ministry of Science and Higher Education (to N.A.C., A.V.L., E.N.F., M.L.M., A.Y.M., N.V.P. and E.A.B.-O.). Sequencing of PCR amplicons was performed using the scientific equipment of the core research facility ‘Bioengineering’ by T. Kolganova. The proteomics analysis was performed at the Proteomics Facility of the Spanish National Center for Biotechnology (CNB-CSIC), which belongs to ProteoRed, PRB2-ISCIII, supported by grant PT13/0001 (to S.C., M.C.M. and M.F.). P.N.G. acknowledges funding from the UK Biotechnology and Biological Sciences Research Council (BBSRC) within the ERA NET-IB2 programme, grant number ERA-IB-14-030 and the European Union Horizon 2020 Research and Innovation programme (Blue Growth: Unlocking the Potential of Seas and Oceans) under grant agreement number 634486, as well as support from the Centre for Environmental Biotechnology project, part funded by the European Regional Development Fund (ERDF) through the Welsh Government, and support from the Centre of Environmental Biotechnology. D.Y.S. was supported by the SIAM/Gravitation Program (Dutch Ministry of Education, Culture and Science; grant 24002002) and RFBR grant 19-04-00401. F.L.S. and S.N. acknowledge support from the Wiener Wissenschafts, Forschungs- und Technologiefonds (Austria) through the grant VRG15-007. F.L.S. gratefully acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation programme (grant agreement 803768). I.A.C.P. acknowledges support from the Fundação para a Ciência e Tecnologia (Portugal) through grant PTDC/BIA-BQM/29118/2017 and R&D unit MOSTMICRO-ITQB (UIDB/04612/2020 and UIDP/04612/2020)