pH和氮素对球等鞭金藻胞外碳酸酐酶活性的影响

采用pH电极法研究pH和氮素对球等鞭金藻胞外碳酸酐酶活性的影响．结果表明，球等鞭金藻具有基本的胞外碳酸酐酶活性，且pH和氮素均能明显地诱导其胞外碳酸酐酶活性．pH从6．5升高到9．0时，球等鞭金藻胞外碳酸酐酶活性明显增加，pH8．5时酶活性达到最大．球等鞭金藻的pH补偿点为9．86，表明其具有利用HC03-的能力．氮素对胞外碳酸酐酶活性诱导也具有重要的影响，3种氮素NH4Cl、NaNOM3、CO（NH2）2在2．0mmoL／L时诱导的酶活性均明显高于8．5mmoL／L时的诱导的酶活性，且有机氮诱导的酶活性明显大于无机氮诱导的酶活性，硝态氮诱导的酶活性大于氨态氮诱导的酶活性．

Effect of pH Value and Nitrogen on Activities of Extracellular Carbonic Anhydrase in Isochrysis galbana

The effects of pH value and nitrogens on activities of extracellular carbonic anhydrase in Isochrysis galbana are studied by the method of pH electrode. The results show that lsochrysis galbana has the basic activities of extracellular carbonic anhydrase which can be induced obviously by both pH value and nitrogen. It is found that the activities of extracellular carbonic anhydrase in Isochrysis galbana increase apparently when pH value rises from 6.5 to 9.0. The highest activity is induced at pH 8.5. And the experiment shows that pH compensation point of lsochrysis galbana is 9.86, which suggests Isochrysis galbana can utilize HCO3^-. Nitrogen is an important regulation factor of extracellular CA expression. The higher extracellular CA activity is induced at 2.0 mmol/L concentration, the extracellular CA activity at 8.5mmol/L concentration is obviously lower than that of at 2. 0 mmol/L. The extracellular CA activity induced in culture solution of NH2 - N is highest in the three kinds of nitrogens, and the activity induced of NO3 - N is higher than that of NH4 - N.