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 Isochrysis 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 Isochrysis galbana is 9.86, which suggests Isochrysis galbana can utilize HCO-3. 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.