Sources of inorganic carbon for marine microalgal photosynthesis: A reassessment of δ13C data from batch culture studies of Thalassiosira pseudonana and Emiliania huxleyi
Sources of inorganic carbon for marine microalgal photosynthesis: A reassessment of δ13C data from batch culture studies of Thalassiosira pseudonana and Emiliania huxleyi
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海洋微藻光合作用的无机碳来源：对假微型海链藻和赫氏艾米利亚藻分批培养研究中的 δ13C 数据进行重新评估
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
Robert R. Bidigure
中科院分区：
文献类型：
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作者：
Edward A. Laws;P. Thompson;B. Popp;Robert R. Bidigure
对先前发表的假海藻（Thalassiosira pseudonana）和赫胥黎Emiliania huxleyi分批培养的稳定碳同位素分离分析的重新评估表明，使用瑞利蒸馏模型来模拟δ13C吸收是错误的。正确使用该模型表明，在收获时，颗粒有机碳（δp）的δ13C与溶解无机碳（DIC）浓度之间的关系同样可以用假设碳酸氢盐或二氧化碳吸收的模型来描述。生长速率与δp之间缺乏相关性，表明生长速率与胞内CO2浓度成正比。理论上的考虑表明，在收获前，在pH值为9.2的条件下开始培养的假单胞菌将会受到二氧化碳的限制，当二氧化碳变得有限时，这个物种必须有利用碳酸氢盐的能力。从pH 8.2和9.2开始培养的假单胞菌δp结果的相似性表明，在两组实验中，DIC进入细胞的形式是相同的。结果与(1)碳酸氢盐被吸收或(2)二氧化碳被吸收一致，当后者受到限制时，外部碳酸酐介导的碳酸氢盐转化为二氧化碳补充了非催化的二氧化碳供应。对赫胥黎赤霉素中颗粒有机碳和球粒碳的δ13C分析表明，细胞在低生长速率下主要吸收碳酸氢盐，而在高生长速率下，用于光合作用的DIC几乎完全来自二氧化碳的吸收。用于球岩芯形成的DIC似乎已被高生长速率下由呼吸作用产生的同位素轻DIC大大稀释。
A reevaluation of previously published analyses of stable carbon isotope fractionation by batch cultures of Thalassiosira pseudonana and Emiliania huxleyi indicates that the Rayleigh distillation model was used to model δ13C uptake incorrectly. Correct use of the model shows that the relationship between the δ13C of the particulate organic carbon (δp) and the concentration of the dissolved inorganic carbon (DIC) at the time of harvest can be equally well described by a model assuming bicarbonate or CO2 uptake. The lack of a correlation between growth rate and δp in the T. pseudonana results suggests that growth rate and the intracellular CO2 concentration are directly proportional. Theoretical considerations indicate that the T. pseudonana cultures started at a pH of 9.2 would have become CO2 limited before harvest and that this species must have the ability to utilize bicarbonate when CO2 becomes limiting. The similarity of the T. pseudonana δp results from cultures started at pH 8.2 and 9.2 suggests that the form of DIC entering the cells was the same in both sets of experiments. The results are consistent with (1) uptake of bicarbonate or (2) uptake of CO2, with external carbonic anhydrasemediated conversion of bicarbonate to CO2 supplementing the uncatalyzed supply of CO2 when the latter becomes limiting. Analysis of the δ13C of both particulate organic carbon and coccolith carbon in the case of E. huxleyi suggests that the cells were taking up primarily bicarbonate at low growth rates, but that at high growth rates the DIC used for photosynthesis was derived almost entirely from uptake of CO2. The DIC utilized for coccolith formation seems to have been substantially diluted by isotopically light DIC derived from respiration at high growth rates.