Massive light-dependent cycling of inorganic carbon between oxygenic photosynthetic microorganisms and their surroundings
Massive light-dependent cycling of inorganic carbon between oxygenic photosynthetic microorganisms and their surroundings
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DOI：
10.1023/a:1025869600935
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发表时间：
2004
影响因子：
3.7
通讯作者：
D. Tchernov;J. Silverman;B. Luz;L. Reinhold;A. Kaplan
中科院分区：
文献类型：
--
作者：
D. Tchernov;J. Silverman;B. Luz;L. Reinhold;A. Kaplan
膜入口质谱表明大量的光依赖性无机碳之间的介质和各种浮游植物物种的细胞代表的主要群体的水生初级生产者的循环。这些包括硅藻，共生和自由生活的甲藻，球石藻，一个绿色蓝藻和丝状和单细胞蓝藻。这些生物可以保持环境中的CO2浓度大大高于或低于与HCO 3 −的化学平衡。随着光照强度的增加，球石藻从净CO2吸收转变为净CO2排放。CO2吸收和CO2固定对光照强度变化的不同反应支持了这两个过程没有强制联系的观点。集球藻CO2和O2交换及荧光参数的同时测定菌株PCC 7942的CO2吸收量可以作为光合反应中心能量状态的敏感探针。然而，在光强度的转换，在CO2吸收的变化并不符合雅阁从荧光变化的预期。对稳定状态下CO2、HCO 3 −和光合作用净通量的量化表明，在“CO2使用者”的情况下，大量HCO 3 −流出伴随着CO2吸收和固定。另一方面，“HCO 3-使用者”的特点是CO2净吸收率低于CO2固定率。这些结果支持这样的观点，即与CCM功能相关的实体不仅可以提高Rubisco位点的CO2浓度，还可以通过耗散多余的光能来减少光动力损伤。
Membrane inlet mass spectrometry indicated massive light-dependent cycling of inorganic carbon between the medium and the cells of various phytoplankton species representing the main groups of aquatic primary producers. These included diatoms, symbiotic and free living dinoflagellates, a coccolithophorid, a green alga and filamentous and single cell cyanobacteria. These organisms could maintain an ambient CO2concentration substantially above or below that expected at chemical equilibrium with HCO3−. The coccolithophoridEmiliania huxleyishifted from net CO2uptake to net CO2efflux with rising light intensity. Differing responses of CO2uptake and CO2fixation to changing light intensity supported the notion that these two processes are not compulsorily linked. Simultaneous measurements of CO2and O2exchange and of the fluorescence parameters inSynechococcussp. strain PCC 7942, showed that CO2uptake can serve as a sensitive probe of the energy status of the photosynthetic reaction centers. However, during transitions in light intensity, changes in CO2uptake did not accord with those expected from fluorescence change. Quantification of the net fluxes of CO2, HCO3−and of photosynthesis at steady-state revealed that substantial HCO3−efflux accompanied CO2uptake and fixation in the case of `CO2users'. On the other hand, `HCO3−users' were characterized by a rate of net CO2uptake below that of CO2fixation. The results support the notion that entities associated with the CCM function not only in raising the CO2concentration at the site of Rubisco; they may also serve as a means of diminishing photodynamic damage by dissipating excess light energy.