Project description:<p>Algal blooms are hotspots of primary production in the ocean, forming the basis of the marine food web and fueling the dissolved organic matter (DOM) pool. Marine viruses are key players in controlling algal bloom demise, thereby diverting algal biomass from higher trophic levels to the DOM pool, a process termed the ‘viral shunt’. To decode the metabolic footprint of the ‘viral shunt’ in the marine environment, we induced a bloom of <em>Emiliania huxleyi</em> and followed its succession using an untargeted exometabolomics approach. Here, we show that algal bloom succession induces dynamic changes in the exometabolic landscape. We discovered a set of novel chlorine-iodine-containing metabolites that were induced by viral infection and released during bloom demise. These metabolites were further detected in virus-infected oceanic <em>E. huxleyi</em> blooms. Therefore, we propose that halogenation with both chlorine and iodine is a distinct hallmark of the virus-induced DOM of <em>E. huxleyi</em>, providing insights into the metabolic consequences of the ‘viral shunt’ for marine DOM.</p>
2021-05-05 | MTBLS1720 | MetaboLights
Project description:Macrogenomes of bacteria during algal bloom
| PRJNA1180447 | ENA
Project description:Crassostrea gigas exposed to toxic dinoflagellate Gymnodinium catenatum
Project description:<p>The viral shunt is a fundamental ecosystem process which diverts the flux of organic carbon fixed through photosynthesis during algal bloom events from heterotrophic grazers to bacteria. Through the extracellular release of metabolites, lytic viral infections supply 2-10% of photosynthetically fixed carbon in the ocean for bacterial respiration. Despite its significance for the carbon cycle, we lack tools to detect the viral shunt in the natural environment and assess its ecological impact. Here, we investigated the use of exometabolites as biomarkers for the viral shunt by applying molecular, metabolomics, and oceanographic tools to study bloom dynamics of the cosmopolitan microalga <em>Gephyrocapsa huxleyi</em> (formerly <em>Emiliania huxleyi</em>) across the Atlantic Ocean, spanning four biogeochemical provinces between Iceland and Patagonia. We mapped the distinct metabolic footprint of its viral infections using exo- and endometabolomics and detected nineteen organohalogen metabolites across the blooms, showing their global distribution. A time-resolved comparison of particulate and dissolved metabolite pools during an induced mesocosm bloom revealed that virocells – actively infected host cells – were the source of the halogenated metabolites. Three trichloro-iodo metabolites were present during the demise of all virus-infected blooms, highlighting them as suitable metabolic biomarkers for the viral shunt. The environmental stability of these halometabolites in the DOM pool over a few days can recapitulate viral infections at earlier stages of phytoplankton bloom succession. The chloro-iodo metabolites thereby expand the existing repertoire of metabolic biomarkers for viral infections at sea and may advance efforts to trace the biogeochemical impact of alga-virus interactions in the surface ocean.</p>