PHOTOSYNTHESIS AND PHOTOSYNTHESIS-COUPLED RESPIRATION IN NATURAL BIOFILMS QUANTIFIED WITH OXYGEN MICROSENSORS
PHOTOSYNTHESIS AND PHOTOSYNTHESIS-COUPLED RESPIRATION IN NATURAL BIOFILMS QUANTIFIED WITH OXYGEN MICROSENSORS
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DOI：
10.1111/j.0022-3646.1992.00051.x
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发表时间：
1992-02-01
影响因子：
2.9
通讯作者：
REVSBECH, NP
中科院分区：
文献类型：
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作者：
GLUD, RN;RAMSING, NB;REVSBECH, NP
利用氧气微传感器对天然生物膜的光合作用和呼吸作用进行了分析。总光合作用的深度剖面由消光后最初几秒钟内O2浓度的下降速率获得，光合作用的净光合作用由稳态时测量的O2浓度梯度计算。光区内的呼吸作用是以总光合作用和净光合作用之差计算的。研究了两种类型的生物膜：一种以硅藻为主，另一种以蓝藻为主。较高的O2/CO2比导致呼吸作用增强，特别是在硅藻生物膜内，这表明光呼吸是主要的耗氧过程。即使在高O2/CO2比刺激呼吸时，两种生物膜内的呼吸速率在消光后的前4.6%S期间也是恒定的。黑暗时期呼吸速率恒定的假设是利用氧气微型传感器测定总光合作用活性的基本假设。在这里，我们提出了证实这一假设的第一个证据。这些结果强烈表明，使用氧气微型传感器测量的总光合作用可能包括随后通过光呼吸失去的碳当量。对S暗培养1.1、1.6和2.6后测量的光合作用剖面的计算机模拟表明，如果可以在时间O进行测定，实际的光合作用剖面可能会出现。在长达4.6%-S的黑暗培养期间，氧气的扩散不会影响整个深度的总光合作用速率，但光合作用活动的表观垂直分布受到强烈影响。
Photosynthesis and respiration were analyzed in natural biofilms by use of O2 microsensors. Depth profiles of gross photosynthesis were obtained from the rate of decrease in O2 concentration during the first few seconds following extinction of light, and net photosynthesis of the photic zone was calculated from O2 concentration gradients measured at steady state. Respiration within the photic zone was calculated as the difference between gross and net photosynthesis. Two types of biofilms were investigated: one dominated by diatoms, and one dominated by cyanobacteria. High O2/CO2 ratios caused increased respiration especially within the diatom biofilm, which could indicate that photorespiration was a dominant O2-consuming process. The rate of respiration was constant within both biofilms during the first 4.6 s following extinction of light, even when respiration was stimulated by high O2/CO2 ratio. The assumption of a constant rate of respiration during the dark period is an essential one for the determination of gross photosynthetic activity by use of O2 microsensors. We here present the first evidence to substantiate this assumption. The results strongly suggest that gross photosynthesis as measured by use of O2 microsensors may include carbon equivalents that are subsequently lost through photorespiration. Computer modeling of photosynthesis profiles measured after 1.1, 1.6, and 2.6 s of dark incubation illustrated how the actual photosynthesis profile could have appeared if it had been possible to do the determination at time O. Diffusion of O2 during the up to 4.6-s long dark incubations did not affect gross photosynthetic rate when integrated over all depths, but the apparent vertical distribution of the photosynthetic activity was strongly affected.