[Objective] To study the effects of saturated CO2 on the growth of Platymonus subcordiformis and the activities of intracellular and extracellular carbonic anhydrases.[Method] CO2 was bubbled to saturate at the beginning of light phase of every light cycle,and then,the biomass,the chlorophyll content and the carbonic anhydrase specific activity of P.subcordiformis were determined at the end of dark phase of every light cycle.[Result] Compared with the control group without bubbling CO2,the lag phase of growth shortened,and the biomass increased obviously during the fast growing period in the medium with bubbling CO2 meanwhile,the biomass of P.subcordiformis,the contents of chlorophyll a and b,and the activities of intracellular,extracellular and total carbonic anhydrases were 1.19,1.75,1.66,1.32,1.26 and 1.43 times of those in the medium without bubbling CO2,respectively.[Conclusion] When the medium was saturated by CO2,P.subcordiformis kept high photosynthetic efficiency to grow fast by increasing the activities of intracellular and extracellular carbonic anhydrases.%[目的]研究饱和CO2对亚心形扁藻生长及细胞内、外碳酸酐酶活性的影响.[方法]在每个光周期的光照阶段开始时通入CO2至饱和,在每个光周期的黑暗阶段结束时取样测定亚心形扁藻细胞的生物量、叶绿素含量及碳酸酐酶比活性.[结果]与未通入CO2的对照组相比,通入CO2至饱和时亚心形扁藻的适应期缩短,进入生长期后生物量增加明显,至培养结束时的生物量、叶绿素a和叶绿素b含量、细胞内外碳酸酐酶、总碳酸酐酶比活性分别是对照组的1.19、1.75、1.66、1.32、1.26、1.43倍.[结论]在培养体系中通入CO2至饱和时,亚心形扁藻通过提高细胞内、外碳酸酐酶的活性来保持高光合作用效率,促进自身生长繁殖.
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