环境因子对铜绿微囊藻7820胞外多糖的影响

Effects of Environmental Factors on Extracellular Polysaccharide Produced by Microcystis aeruginosa PCC7820

研究了多种环境因子对铜绿微囊藻7820可溶性胞外多糖(extracellular polysaccharide,EPS)合成的影响.在18 d内,较高浓度的NO3-,较高的pH和光强,均显著提高了EPS的合成,其中,NO3-对EPS的合成影响最大,其最大产率为5.255μg.L-1.d-1.而KH2PO4,CaCl2,MgSO4等大量元素、以及微量元素FeCl3和EDTA对EPS的合成无明显影响;除在实验后期20℃时EPS有较大增加外,温度对其无明显影响.在各种环境因子影响下,EPS产量均随时间延长而增加.此外,NO3-,pH和光强对铜绿微囊藻7820的生长速率和总糖的产生也有影响,在较低的NO3-浓度、适中的pH和光强下,生长速率较高;而较高的NO3-浓度、较低的pH和光强,其生长速率明显较低;略低的NO3-浓度和光强可明显提高其总糖产量,而较高的NO3-浓度和弱的光强则明显降低其总糖产量;pH对总糖的产量影响不大.微囊藻有较高的多糖积累,其EPS和总糖的合成有不同的机制.

A study on the effects of environmental factors on the synthesis of soluble polysaccharides in Microcystis aerginosa PCC 7820 was carried out. In 18 days, the higher NO3^- concentration, the higher pH and light intensity enhanced the synthesis of extracellular polysaccharide （EPS）, and NO3^- concentration,which maximum EPS accumulation rate was 5. 255μg·L^-1·d^-1, had more drastically effect on EPS production than pH and light intensity. However, KH2PO4 ,CaCl2,MgSO4, FeCl3, and EDTA had little effect on EPS production, and temperature had no obvious effect except that EPS had increased at 20 ℃ in the late stage of the experiment. Under the different environmental factor, EPS production increased with the time prolonging. In addition, NO3^- concentration, pH and light intensity had different effect on maximum growth rate and total carbohydrate, the lower NO3^- concentration, moderate pH and light intensity had the higher growth rate but it significantly decreased in the higher NO3^- concentration, the lower pH and light intensity; total carbohydrate significantly increased in the lower NO3^- concentration and light intensity but the higher NO3^- concentration and weak light intensity decreased it; and total carbohydrate yield was not influenced obviously by pH. M. aeruginosa had high polysaccharide accumulation rate. The mechanism of EPS＇s synthesis is different from that of the total carbohydrate synthesis.