洱海螺旋鱼腥藻生长生理特性的初步研究

近年来，洱海正处于中营养水平向富营养湖泊的过渡阶段，蓝藻水华也频繁发生。本文作者在洱海大规模水华暴发期间，分离、纯化了水华优势种螺旋鱼腥藻，并对其生长生理特性进行了初步研究，以期为探讨洱海鱼腥藻水华发生的环境影响因素提供基础的参考资料。实验结果表明，氮含量1.5mmol/L、磷含量12µmol/L、光照强度30E/ m·s、pH值8－10及温度25℃时，螺旋鱼腥藻生长状况最好，生物量及相对生长速率较高。不同氮、磷浓度下的氮磷代谢活性表明：氮浓度在0－0.36mmol/L时，硝酸还原酶活性随着氮浓度的增加而增强；氮浓度在0.36－6 mmol/L时，酶活性由其生长状况决定，生长越好，酶活性越高。碱性磷酸酶受磷影响较大，随着磷浓度的增加其活性逐渐减弱，磷充足时，氮对其活性并无显著影响。此外，洱海螺旋鱼腥藻可在低的氮、磷浓度下生长，这与其氮磷代谢活性的调节作用有关。

A study on the growth and some physiological characteristics of Anabaena spiroides isolated from Lake Erhai

In recent years, Lake Erhai is experiencing a transition from the mesotrophic to eutrophic condition and cya-nobacterial blooms have a rapid increase in the lake. In this study, the dominant species from the bloom of Lake Erhai, Anabaena spiroides, was isolated and purified. The growth and physiological characteristics of an Anabaena spiroides strain under different environmental conditions were studied to evaluate the influence of environmental factors on Anabaena bloom formation, and the growth was determined by cell biomass and relative growth rate. The results showed that the Anabaena the contents of nitrogen 1.5mmol/L and phosphorus 12μmol/L. The activities of nitrate reductase (NR) and alkaline phophatase (APA), which indicate metabolism of nitrogen and phosphorus, were measured with different concentrations of nitrogen and phosphorus. NR activity of the Anabaena spiroicles strain increased with the raising of nitrogen concentration when nitrogen supply level was low (0-0.36 mmol/L). But the activity of NR was related to the growth under the condi-tion of rich nitrogen supply (0.36-6 mmol/L), i.e. the better strain's growth, the higher NR activity. APA activity of the Anabaena spiroides strain largely depended on the concentration of phosphorus. APA activity was lower with more phos-phorus supply. And Nitrogen did not play an important role in the activity change of APA when phosphorus supply was rich. In addition, it was observed that the Anabaena spiroides strain could grow with low concentration of nitrogen or phos-phorus. This may be related to special regulatory mechanism of nitrogen fixing and phosphorus utilizing of Anabaena.