Metabolic Microenvironmental Control by Photosynthetic Biofilms under Changing Macroenvironmental Temperature and pH Conditions
Metabolic Microenvironmental Control by Photosynthetic Biofilms under Changing Macroenvironmental Temperature and pH Conditions
复制标题
宏观环境温度和 pH 条件变化下光合生物膜的代谢微环境控制
DOI：
10.1128/aem.00877-08
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发表时间：
2008
影响因子：
4.4
通讯作者：
G. Arp
中科院分区：
文献类型：
--
作者：
A. Bissett;A. Reimer;D. de Beer;F. Shiraishi;G. Arp
摘要采用微电极原位实验方法，研究了不同pH值、温度和碱度条件下，岩溶水体中蓝藻生物膜的光合作用对蓝藻钙化的影响。钙化点周围的微环境化学条件控制的代谢活动在很宽的范围内的光合作用和呼吸速率，上覆水条件的影响不大。无论上覆水的pH值水平（从7.8至8.9），在生物膜表面的pH值约为9.4在光和7.8在黑暗中。在不同温度（4°C和17°C）下观察到相同的趋势。生物过程控制这些和类似系统中的碳酸钙饱和状态（Ω），并且能够在相对宽的环境波动下将Ω维持在近似恒定的水平。然而，温度确实对钙化率有影响。该系统中的钙通量受其扩散系数的限制，导致较高的钙通量（钙化和溶解）在较高的温度下，尽管常数，生物系统减轻环境扰动影响的能力是一个重要因素，在试图预测大气CO2分压增加对钙化等过程的影响时必须考虑以及解释化石记录中的微体化石。
ABSTRACT Ex situ microelectrode experiments, using cyanobacterial biofilms from karst water creeks, were conducted under various pH, temperature, and constant-alkalinity conditions to investigate the effects of changing environmental parameters on cyanobacterial photosynthesis-induced calcification. Microenvironmental chemical conditions around calcifying sites were controlled by metabolic activity over a wide range of photosynthesis and respiration rates, with little influence from overlying water conditions. Regardless of overlying water pH levels (from 7.8 to 8.9), pH at the biofilm surface was approximately 9.4 in the light and 7.8 in the dark. The same trend was observed at various temperatures (4°C and 17°C). Biological processes control the calcium carbonate saturation state (Ω) in these and similar systems and are able to maintain Ω at approximately constant levels over relatively wide environmental fluctuations. Temperature did, however, have an effect on calcification rate. Calcium flux in this system is limited by its diffusion coefficient, resulting in a higher calcium flux (calcification and dissolution) at higher temperatures, despite the constant, biologically mediated pH. The ability of biological systems to mitigate the effects of environmental perturbation is an important factor that must be considered when attempting to predict the effects of increased atmospheric partial CO2 pressure on processes such as calcification and in interpreting microfossils in the fossil record.