Effect of Culture pH on Properties of Exopolymeric Substances from Synechococcus PCC7942: Implications for Carbonate Precipitation

The role of culture conditions on the production exopolymeric substances (EPS) by Synechococcus strain PCC7942 was investigated. Carbonate mineral precipitation in these EPS assessed forced experiments. Cultures were grown HEPES-buffered medium and non-buffered medium. pH buffered remained constant at 7.5, but it increased to 9.5 within a day leveled off 10.5. cell yield harvest twice as high than High molecular weight (>10 kDa) low (3–10 fractions obtained from both cultures. cell-specific cultures contained more negatively charged macromolecules proteins higher protein content elevated may be due induction carbon-concentrating mechanisms, necessary perform photosynthetic carbon fixation conditions. Forced showed smaller calcite carbonate crystals larger minerals polymers Vaterite formed only concentrations. Experimental results are used conceptually model impact potential cyanobacterial blooms produce minerals. We hypothesize that freshwater systems, small crystal benefit picoplankton minimizing ballast, thus prolonging residence time photic zone, which might result slow sinking rates.