Nitrogen flux into metabolites and microcystins changes in response to different nitrogen sources in Microcystis aeruginosa NIES-843 |
| |
| Authors: | Lauren E Krausfeldt Abigail T Farmer Hector F Castro Gregory L Boyer Shawn R Campagna Steven W Wilhelm |
| |
| Institution: | 1. Department of Microbiology, University of Tennessee, Knoxville, TN, USA;2. Department of Chemistry, University of Tennessee, Knoxville, TN, USA;3. Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, NY, USA |
| |
| Abstract: | The over-enrichment of nitrogen (N) in the environment has contributed to severe and recurring harmful cyanobacterial blooms, especially by the non-N2-fixing Microcystis spp. N chemical speciation influences cyanobacterial growth, persistence and the production of the hepatotoxin microcystin, but the physiological mechanisms to explain these observations remain unresolved. Stable-labelled isotopes and metabolomics were employed to address the influence of nitrate, ammonium, and urea on cellular physiology and production of microcystins in Microcystis aeruginosa NIES-843. Global metabolic changes were driven by both N speciation and diel cycling. Tracing 15N-labelled nitrate, ammonium, and urea through the metabolome revealed N uptake, regardless of species, was linked to C assimilation. The production of amino acids, like arginine, and other N-rich compounds corresponded with greater turnover of microcystins in cells grown on urea compared to nitrate and ammonium. However, 15N was incorporated into microcystins from all N sources. The differences in N flux were attributed to the energetic efficiency of growth on each N source. While N in general plays an important role in sustaining biomass, these data show that N-speciation induces physiological changes that culminate in differences in global metabolism, cellular microcystin quotas and congener composition. |
| |
| Keywords: | |
|
|
