Adsorption of nitrogen and phosphorus by intact cells and cell wall polysaccharides of Microcystis

Microcystis blooms can move vertically and horizontally in natural water bodies, which often causes a rapid change of nutritional environment around Microcystis cells. To evaluate the capability of Microcystis capturing nitrogen (N) and phosphorus (P) when environmental nutrient levels change, we studied N and P adsorption of two different forms of Microcystis aeruginosa strains, a colonial strain XW01 and a unicellular strain PCC 7806, and a green alga Chlorella pyrenoidosa to different concentrations of nitrate, ammonium and phosphate in 30 min. The results showed that XW01 had much stronger adsorption capacity than PCC7806 and Chlorella. As main components of the cell wall, the polysaccharides of XW01 displayed different adsorption capacities in different N and P concentrations, their adsorption capabilities rose higher with the N or P concentration increase. Comparing with pH 7.0, XW01 could adsorb much more ammonia and phosphate in alkaline condition (pH 9.0), although the nitrate adsorption decreased a little.