New insights on organic nitrogen assimilation in Microcystis phycosphere and impacts on microcystin production
Start Date
26-5-2022 9:45 AM
End Date
26-5-2022 10:00 AM
Abstract
Microcystis is one of the most globally abundant bloom-forming cyanobacteria, comprising species that produce nitrogen-rich hepatotoxic compounds known as microcystins (MCs). Although dissolved organic nitrogen can exceed 50% of the nitrogen pool in aquatic ecosystems, organic nitrogen compounds are often overlooked in terms of their impact on community dynamics and Microcystis bloom development. Further, cyanobacteria are constantly interacting with other microorganisms in their surrounding environment, but nitrogen cycling in the phycosphere is poorly understood. In the present study, we monitored the growth and MC production of several Microcystis strains on various organic nitrogen sources including amino acids and proteins, investigated the impacts of organic nitrogen on Microcystis microbiome via amplicon and metagenomic sequencing, and traced the nitrogen assimilation within the phycosphere at the single-cell level by measuring isotopic tracer incorporation via secondary ion mass spectrometer imaging (NanoSIMS). We demonstrate that 1) organic nitrogen species shape the microbiome community structure in the Microcystisphycosphere, and 2) competition for and/or transport of nitrogen between heterotrophic bacteria and cyanobacteria potentially play important roles for cyanobacterial succession especially under inorganic nitrogen scarcity.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
New insights on organic nitrogen assimilation in Microcystis phycosphere and impacts on microcystin production
Microcystis is one of the most globally abundant bloom-forming cyanobacteria, comprising species that produce nitrogen-rich hepatotoxic compounds known as microcystins (MCs). Although dissolved organic nitrogen can exceed 50% of the nitrogen pool in aquatic ecosystems, organic nitrogen compounds are often overlooked in terms of their impact on community dynamics and Microcystis bloom development. Further, cyanobacteria are constantly interacting with other microorganisms in their surrounding environment, but nitrogen cycling in the phycosphere is poorly understood. In the present study, we monitored the growth and MC production of several Microcystis strains on various organic nitrogen sources including amino acids and proteins, investigated the impacts of organic nitrogen on Microcystis microbiome via amplicon and metagenomic sequencing, and traced the nitrogen assimilation within the phycosphere at the single-cell level by measuring isotopic tracer incorporation via secondary ion mass spectrometer imaging (NanoSIMS). We demonstrate that 1) organic nitrogen species shape the microbiome community structure in the Microcystisphycosphere, and 2) competition for and/or transport of nitrogen between heterotrophic bacteria and cyanobacteria potentially play important roles for cyanobacterial succession especially under inorganic nitrogen scarcity.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344