A laboratory experiment was conducted to study the influence of nutrients (nitrogen and phosphorus) on the component of Microcystis cells (polysaccharide,protein,and RNA).These biochemical parameters were analyzed during the logarithmic phase.Results showed that the concentrations of N and P had limited effect on the content of RNA,which was relatively constant in each cell (about 2.0 pg/cell).However,the cellular contents of protein and polysaccharide were significantly affected by the N concentrations.The protein content was notably increased with the increase of N concentration,and the total polysaccharide content remarkably decreased on the contrary.The influence of P concentration on the total polysaccharide content was similar to that of N concentration,however,it showed little effects on protein content (nearly 4.6 pg/cell).The increase of N concentration could also promote intracellular polysaccharide (IPS) transform to extracellular polysaccharide (EPS),and the soluble part of EPS increased.Besides,the RNA and protein were rapidly synthesized when cells were in high growth rate,which caused the polysaccharide synthesis was too slow to produce enough extracellular polysaccharide for colony formation.Thus,it was difficult to form colonies during the laboratory incubation.