Wannicke, Nicola;
Herrmann, Achim;
Gehringer, Michelle M.
Atmospheric CO2 availability induces varying responses in net photosynthesis, toxin production and N2 fixation rates in heterocystous filamentous Cyanobacteria (Nostoc and Nodularia)
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Medientyp:
E-Artikel
Titel:
Atmospheric CO2 availability induces varying responses in net photosynthesis, toxin production and N2 fixation rates in heterocystous filamentous Cyanobacteria (Nostoc and Nodularia)
Beteiligte:
Wannicke, Nicola;
Herrmann, Achim;
Gehringer, Michelle M.
Erschienen:
Springer Science and Business Media LLC, 2021
Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Heterocystous Cyanobacteria of the genus <jats:italic>Nodularia</jats:italic> form major blooms in brackish waters, while terrestrial <jats:italic>Nostoc</jats:italic> species occur worldwide, often associated in biological soil crusts. Both genera, by virtue of their ability to fix N<jats:sub>2</jats:sub> and conduct oxygenic photosynthesis, contribute significantly to global primary productivity. Select <jats:italic>Nostoc</jats:italic> and <jats:italic>Nodularia</jats:italic> species produce the hepatotoxin nodularin and whether its production will change under climate change conditions needs to be assessed. In light of this, the effects of elevated atmospheric CO<jats:sub>2</jats:sub> availability on growth, carbon and N<jats:sub>2</jats:sub> fixation as well as nodularin production were investigated in toxin and non-toxin producing species of both genera. Results highlighted the following:<jats:list list-type="bullet">
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<jats:p>Biomass and volume specific biological nitrogen fixation (BNF) rates were respectively almost six and 17 fold higher in the aquatic <jats:italic>Nodularia</jats:italic> species compared to the terrestrial <jats:italic>Nostoc</jats:italic> species tested, under elevated CO<jats:sub>2</jats:sub> conditions.</jats:p>
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<jats:p>There was a direct correlation between elevated CO<jats:sub>2</jats:sub> and decreased dry weight specific cellular nodularin content in a diazotrophically grown terrestrial <jats:italic>Nostoc</jats:italic> species, and the aquatic <jats:italic>Nodularia</jats:italic> species, regardless of nitrogen availability.</jats:p>
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<jats:p>Elevated atmospheric CO<jats:sub>2</jats:sub> levels were correlated to a reduction in biomass specific BNF rates in non-toxic <jats:italic>Nodularia</jats:italic> species.</jats:p>
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<jats:p>Nodularin producers exhibited stronger stimulation of net photosynthesis rates (NP) and growth (more positive Cohen’s d) and less stimulation of dark respiration and BNF per volume compared to non-nodularin producers under elevated CO<jats:sub>2</jats:sub> levels.</jats:p>
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</jats:list></jats:p><jats:p>This study is the first to provide information on NP and nodularin production under elevated atmospheric CO<jats:sub>2</jats:sub> levels for <jats:italic>Nodularia</jats:italic> and <jats:italic>Nostoc</jats:italic> species under nitrogen replete and diazotrophic conditions.</jats:p>