Effect of Culture pH on Properties of Exopolymeric Substances from <i>Synechococcus</i> PCC7942: Implications for Carbonate Precipitation
The role of culture conditions on the production of exopolymeric substances (EPS) by <i>Synechococcus</i> strain PCC7942 was investigated. Carbonate mineral precipitation in these EPS was assessed in forced precipitation experiments. Cultures were grown in HEPES-buffered medium and non-b...
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MDPI AG
2022-05-01
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| Online Access: | https://www.mdpi.com/2076-3263/12/5/210 |
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| author | Marlisa Martinho de Brito Irina Bundeleva Frédéric Marin Emmanuelle Vennin Annick Wilmotte Laurent Plasseraud Pieter T. Visscher |
| author_facet | Marlisa Martinho de Brito Irina Bundeleva Frédéric Marin Emmanuelle Vennin Annick Wilmotte Laurent Plasseraud Pieter T. Visscher |
| author_sort | Marlisa Martinho de Brito |
| collection | DOAJ |
| description | The role of culture conditions on the production of exopolymeric substances (EPS) by <i>Synechococcus</i> strain PCC7942 was investigated. Carbonate mineral precipitation in these EPS was assessed in forced precipitation experiments. Cultures were grown in HEPES-buffered medium and non-buffered medium. The pH of buffered medium remained constant at 7.5, but in non-buffered medium it increased to 9.5 within a day and leveled off at 10.5. The cell yield at harvest was twice as high in non-buffered medium than in buffered medium. High molecular weight (>10 kDa) and low molecular weight (3–10 kDa) fractions of EPS were obtained from both cultures. The cell-specific EPS production in buffered medium was twice as high as in non-buffered medium. EPS from non-buffered cultures contained more negatively charged macromolecules and more proteins than EPS from buffered cultures. The higher protein content at elevated pH may be due to the induction of carbon-concentrating mechanisms, necessary to perform photosynthetic carbon fixation in these conditions. Forced precipitation showed smaller calcite carbonate crystals in EPS from non-buffered medium and larger minerals in polymers from buffered medium. Vaterite formed only at low EPS concentrations. Experimental results are used to conceptually model the impact of pH on the potential of cyanobacterial blooms to produce minerals. We hypothesize that in freshwater systems, small crystal production may benefit the picoplankton by minimizing the mineral ballast, and thus prolonging the residence time in the photic zone, which might result in slow sinking rates. |
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| issn | 2076-3263 |
| language | English |
| last_indexed | 2024-03-10T03:49:20Z |
| publishDate | 2022-05-01 |
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| series | Geosciences |
| spelling | doaj.art-73fac0c3b3df4b7992aa2086773cb5902023-11-23T11:12:20ZengMDPI AGGeosciences2076-32632022-05-0112521010.3390/geosciences12050210Effect of Culture pH on Properties of Exopolymeric Substances from <i>Synechococcus</i> PCC7942: Implications for Carbonate PrecipitationMarlisa Martinho de Brito0Irina Bundeleva1Frédéric Marin2Emmanuelle Vennin3Annick Wilmotte4Laurent Plasseraud5Pieter T. Visscher6Biogeosciences Laboratory, Department of Life, Earth and Environmental Sciences, University of Bourgogne Franche-Comté, 21000 Dijon, FranceBiogeosciences Laboratory, Department of Life, Earth and Environmental Sciences, University of Bourgogne Franche-Comté, 21000 Dijon, FranceBiogeosciences Laboratory, Department of Life, Earth and Environmental Sciences, University of Bourgogne Franche-Comté, 21000 Dijon, FranceBiogeosciences Laboratory, Department of Life, Earth and Environmental Sciences, University of Bourgogne Franche-Comté, 21000 Dijon, FranceInBios-Centre for Protein Engineering, Department of Life Sciences, Faculty of Sciences, University of Liège, 4000 Liège, BelgiumICMUB Institute of Molecular Chemistry (CNRS UMR CNRS 6302), University of Burgundy-Franche-Comté, 21000 Dijon, FranceBiogeosciences Laboratory, Department of Life, Earth and Environmental Sciences, University of Bourgogne Franche-Comté, 21000 Dijon, FranceThe role of culture conditions on the production of exopolymeric substances (EPS) by <i>Synechococcus</i> strain PCC7942 was investigated. Carbonate mineral precipitation in these EPS was assessed in forced precipitation experiments. Cultures were grown in HEPES-buffered medium and non-buffered medium. The pH of buffered medium remained constant at 7.5, but in non-buffered medium it increased to 9.5 within a day and leveled off at 10.5. The cell yield at harvest was twice as high in non-buffered medium than in buffered medium. High molecular weight (>10 kDa) and low molecular weight (3–10 kDa) fractions of EPS were obtained from both cultures. The cell-specific EPS production in buffered medium was twice as high as in non-buffered medium. EPS from non-buffered cultures contained more negatively charged macromolecules and more proteins than EPS from buffered cultures. The higher protein content at elevated pH may be due to the induction of carbon-concentrating mechanisms, necessary to perform photosynthetic carbon fixation in these conditions. Forced precipitation showed smaller calcite carbonate crystals in EPS from non-buffered medium and larger minerals in polymers from buffered medium. Vaterite formed only at low EPS concentrations. Experimental results are used to conceptually model the impact of pH on the potential of cyanobacterial blooms to produce minerals. We hypothesize that in freshwater systems, small crystal production may benefit the picoplankton by minimizing the mineral ballast, and thus prolonging the residence time in the photic zone, which might result in slow sinking rates.https://www.mdpi.com/2076-3263/12/5/210cyanobacteriaexopolymeric substancesEPS<i>Synechococcus</i>carbonate crystal sizepicoplankton bloom |
| spellingShingle | Marlisa Martinho de Brito Irina Bundeleva Frédéric Marin Emmanuelle Vennin Annick Wilmotte Laurent Plasseraud Pieter T. Visscher Effect of Culture pH on Properties of Exopolymeric Substances from <i>Synechococcus</i> PCC7942: Implications for Carbonate Precipitation Geosciences cyanobacteria exopolymeric substances EPS <i>Synechococcus</i> carbonate crystal size picoplankton bloom |
| title | Effect of Culture pH on Properties of Exopolymeric Substances from <i>Synechococcus</i> PCC7942: Implications for Carbonate Precipitation |
| title_full | Effect of Culture pH on Properties of Exopolymeric Substances from <i>Synechococcus</i> PCC7942: Implications for Carbonate Precipitation |
| title_fullStr | Effect of Culture pH on Properties of Exopolymeric Substances from <i>Synechococcus</i> PCC7942: Implications for Carbonate Precipitation |
| title_full_unstemmed | Effect of Culture pH on Properties of Exopolymeric Substances from <i>Synechococcus</i> PCC7942: Implications for Carbonate Precipitation |
| title_short | Effect of Culture pH on Properties of Exopolymeric Substances from <i>Synechococcus</i> PCC7942: Implications for Carbonate Precipitation |
| title_sort | effect of culture ph on properties of exopolymeric substances from i synechococcus i pcc7942 implications for carbonate precipitation |
| topic | cyanobacteria exopolymeric substances EPS <i>Synechococcus</i> carbonate crystal size picoplankton bloom |
| url | https://www.mdpi.com/2076-3263/12/5/210 |
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