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:As an essential micronutrient that is scarce in surface ocean waters, zinc (Zn) has the potential to limit oceanic photosynthetic productivity and influence the global carbon cycle. Here we observed Zn co-limitation with iron (Fe) in the natural phytoplankton community of Terra Nova Bay, Antarctica, induced by the drawdown of seawater CO2 and dZn during a bloom. Incubations amended with Zn resulted in significantly higher chlorophyll a content and greater macronutrient and dissolved inorganic carbon drawdown compared to Fe addition alone. Multiple Zn and Fe response proteins were observed in experimental and water column samples demonstrating co-stress in various algal taxa. Together these results demonstrate that Zn limitation can occur in productive Antarctic coastal ecosystems. Thus, Zn may be an important factor limiting the total productivity potential of marine phytoplankton.
2025-09-29 | PXD037056 | Pride
Project description:Bacterial community dynamics during a harmful algal bloom of Heterosigma akashiwo