Project description:Phytoplankton blooms provoke bacterioplankton blooms, from which bacterial biomass (necromass) is released via increased zooplankton grazing and viral lysis. While bacterial consumption of algal biomass during blooms is wellstudied, little is known about the concurrent recycling of these substantial amounts of bacterial necromass. We demonstrate that bacterial biomass, such as bacterial alpha-glucan storage polysaccharides, generated from the consumption of algal organic matter, is reused and thus itself a major bacterial carbon source in vitro and during a diatom-dominated bloom. We highlight conserved enzymes and binding proteins of dominant bloom-responder clades that are presumably involved in the recycling of bacterial alpha-glucan by members of the bacterial community. We furthermore demonstrate that the corresponding protein machineries can be specifically induced by extracted alpha-glucan-rich bacterial polysaccharide extracts. This recycling of bacterial necromass likely constitutes a large-scale intra-population energy conservation mechanism that keeps substantial amounts of carbon in a dedicated part of the microbial loop.
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:Spatiotemporal changes of bacterial and cyanobacterial communities during an algal bloom
| PRJNA786052 | ENA
Project description:Bacterial community dynamics during a harmful algal bloom of Heterosigma akashiwo
| PRJNA669545 | ENA
Project description:Metagenomic analysis of the Three Gorges Reservoir tributaries during algal bloom
Project description:Laminarin is a major storage polysaccharide in phytoplankton and an important carbon and energy source for marine microbes. How microbes compete for this labile polysaccharide in nature remains unclear. Here we investigated metaproteomes and metagenomes of bacterioplankton during four consecutive algal blooms in the North Sea to determine key laminarin consumers. We identified two specialized laminarin degraders of the Bacteroidetes group, which reached high abundances year after year. We found that these genomically streamlined bacteria of the genus Formosa have an expanded set of laminarin hydrolases, sensors and transporters that belonged to the most abundant proteins in the blooms. The respective genes are organized in three polysaccharide utilization loci. Proteomic and biochemical analyses revealed surface tethered enzymes and a laminarinase recombined with a membrane-spanning transporter, which act as a disassembly line and efficiently integrate substrate degradation and uptake in the highly diffusive, aquatic environment. We also show that the bloom bacteria couple laminarin utilization with uptake of cellular building blocks such as amino acids. This study suggests that in addition to genome reduction, enzyme fusions, transporter and enzyme expansion also the tight coupling of the carbon and nitrogen uptake make Formosa spp. efficient laminarin utilizers.