Photosynthetic bicarbonate utilization in Porphyra haitanensis(Bangiales,Rhodophyta)  

作　　者：ZOU Dinghui GAO Kunshan 

机构地区：[1]Marine Biology Institute,Science Center,Shantou University,Shantou 515063,China [2]Institute of Hydrobiology,Chinese Academy of Sciences,Wuhan 430072,China

出　　处：《Chinese Science Bulletin》2002年第19期1629-1633,共5页

基　　金：This work was supported by the National Natural Science Foundation of China (Grant No. 39830060);the Natural Science Foundation of Guangdong Province.

摘　　要：The activities of carbonic anhydrase (CA) and photosynthesis of Porphyra haitanensis were investigated in order to see its photosynthetic utilization of inorganic carbon source. Both intra- and extra-cellular CA activities existed in the thallus. CA inhibitors, acetazolamide (AZ) and ethoxy-zolamide (EZ), remarkably depressed the photosynthetic oxygen evolution in seawater of pH 8.2 and 10.0, and EZ showed stronger inhibition than AZ. The observed net photosynthetic rate in seawater of pH 8.2 was much higher than that of CO2 supply theoretically derived from spontaneous dehydration of HCO3. P. haitanensis also showed a rather high pH compensation point (9.9). The results demonstrated that P. haitanensis could utilize bicarbonate as the external inorganic carbon source for photosynthesis. The bicarbonateutilization was closely associated with HCO3- dehydrationcatalyzed by extracellular CA activity. The inorganic carbon composition in seawater could well saturate the photosynthesis of P. haitanensis. TheThe activities of carbonic anhydrase (CA) and photosynthesis ofPorphyra haitanensis were investigated in order to see its photosynthetic utilization of inorganic carbon source. Both intra- and extra-cellular CA activities existed in the thallus. CA inhibitors, acetazolamide (AZ) and ethoxy-zolamide (EZ), remarkably depressed the photosynthetic oxygen evolution in seawater of pH 8.2 and 10.0, and EZ showed stronger inhibition than AZ. The observed net photosynthetic rate in seawater of pH 8.2 was much higher than that of CO2 supply theoretically derived from spontaneous dehydration of HCO3 ?.P. haitanensis also showed a rather high pH compensation point (9.9). The results demonstrated thatP. haitanensis could utilize bicarbonate as the external inorganic carbon source for photosynthesis. The bicarbonate utilization was closely associated with HCO3 ? dehydration catalyzed by extracellular CA activity. The inorganic carbon composition in seawater could well saturate the photosynthesis ofP. haitanensis. The low Km value and compensation points for inorganic carbon reflected the existence of CO2-concentrating mechanism in this alga.

关 键 词：PORPHYRA kaitanensis photosynthesis BICARBONATE inor-ganic carbon UTILIZATION carbonic anhydrase. 

分 类 号：Q945[生物学—植物学]