Project description:<p>Phaeocystis pouchetii (Hariot) Lagerheim, 1893 regularly dominates phytoplankton blooms in the Arctic. Through zooplankton grazing and microbial activity, it is considered to be a key resource for the entire marine food web but the actual relevance of biomass transfer to higher trophic levels is still under discussion. Cell physiology and algal nutritional state are suggested to be major factors controlling the observed variability in zooplankton grazing. However, no data have so far yielded insights into the metabolic state of Phaeocystis populations that would allow testing this hypothesis. Therefore, endometabolic markers of different growth phases were determined in laboratory batch cultures using comparative metabolomics and quantified in different phytoplankton blooms in the field. Metabolites, produced during exponential, early and late stationary growth of P. pouchetii were profiled using gas chromatography-mass spectrometry. Then, metabolites were characterized that correlate with the growth phases using multivariate statistical analysis. Free amino acids characterized exponential growth, whereas the early stationary phase was correlated with sugar alcohols, mono- and disaccharides. In the late stationary phase free fatty acids, sterols and terpenes increased. These marker metabolites were then traced in Phaeocystis blooms during a cruise in the Barents Sea and North Norwegian fjords. About 50 endometabolites of P. pouchetii were detected in natural phytoplankton communities. Their relative abundances at Phaeocystis-dominated stations differed from diatom-dominated stations. Mannitol, scyllo- inositol, 24-methylcholesta-5,22-dien-3β-ol, and several free fatty acids were characteristic for Phaeocystis-dominated blooms. Distinct metabolic profiles were detected in the nutrient- depleted community in the inner Porsangerfjord (<0.5 μM NO3-, <0.1 μM PO4-), with high relative amounts of free mono- and disaccharides indicative for a limited culture. This study, therefore, shows how variable physiology of phytoplankton can alter the metabolic landscape of entire plankton communities.</p>
Project description:The available energy and carbon sources for prokaryotes in the deep ocean remain still largely enigmatic. Reduced sulfur compounds, such as thiosulfate, are a potential energy source for both auto- and heterotrophic marine prokaryotes. Shipboard experiments performed in the North Atlantic using Labrador Sea Water (~2000 m depth) amended with thiosulfate led to an enhanced prokaryotic dissolved inorganic carbon (DIC) fixation.
Project description:In this project, the metaproteome of the marine bacterioplankton was analyzed to assess its respone towards an algal bloom in the southern North Sea in spring 2010. Proteins were extracted applying two different methods: (i) applying chemical cell lysis using trifluoroethanol in combination with in-solution digest and (ii) mechanical cell lysis applying bead beating, SDS-PAGE prefractionation and in-gel digest. Both samples were analyzed by nanoLC and ESI-iontrap MS. In case of the TFE lysis samples, also nanoLC-MALDI-TOF MS was applied.
2017-04-11 | PXD004944 | Pride
Project description:COI metabarcoding of river eDNA samples
| PRJNA1214582 | ENA
Project description:Zooplankton metabarcoding
| PRJNA362520 | ENA
Project description:18S & COI mesozooplankton metabarcoding - Eastern North Pacific 0-1000m
Project description:The experiment compared flounder from the North Sea and the Baltic sea and their reactions on being exposed to water of different salinities
Project description:Vibrio species represent one of the most diverse genera of marine bacteria known for their ubiquitous presence in natural aquatic systems. Several members of this genus including Vibrio harveyi are receiving increasing attention lately because they are becoming a source of health problems, especially for some marine organisms widely used in sea food industry. To learn about adaptation changes triggered by V. harveyi during its long-term persistence at elevated temperatures, we studied adaptation of this marine bacterium in sea water microcosms at 30 oC that closely mimicks the upper limits of sea surface temperatures recorded around the globe.
