营养盐对微囊藻细胞组分及多糖组成的影响

Effect of nutrients on components and polysaccharide content of Microcystis cells

胞外多糖是微囊藻形成群体的物质基础,营养盐是否会通过影响微囊藻多糖的含量进而影响群体的形成还不清楚.在室内培养实验中,设置不同N、P浓度的培养液并测定对数期胞内的细胞组分以及3种形态的多糖含量,从而探讨N、P对细胞中多糖的影响规律.实验结果表明:RNA在细胞中的含量相对恒定(约2.0 pg/cell).N对单细胞的蛋白质和多糖都产生了显著影响:N浓度的升高显著促进蛋白质的合成,细胞中总糖的含量降低.P浓度的升高同样造成细胞中多糖总量减少,但其对蛋白质影响不大(在4.6 pg/cell左右波动).N浓度的增加还促进多糖向胞外分泌并溶解于培养基中.在高生长率下,由于细胞中RNA、蛋白质的合成速度加快,多糖的合成较慢导致胞外固着性多糖减少,这可能是室内培养难以得到群体的原因之一.

A laboratory experiment was conducted to study the influence of nutrients （nitrogen and phosphorus） on the component of Microcystis ceils （ polysaecharide, 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 al- so promote intracellular polysaccharide （IPS） transform to extracellular polysaccharide （EPS） , and the soluble part of EPS in- creased. Besides, the RNA and protein were rapidly synthesized when cells were in high growth rate, which caused the polysaccha- ride synthesis was too slow to produce enough extracellular polysaccharide for cdlony formation. Thus, it was difficult to form colo- nies during the laboratory incubation.