Characterization of CO2 fixation on algal biofilms with an infrared gas analyzer and importance of a space-rich structure on the surface
Characterization of CO2 fixation on algal biofilms with an infrared gas analyzer and importance of a space-rich structure on the surface
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DOI：
10.1016/j.algal.2020.101814
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发表时间：
2020-03-01
影响因子：
5.1
通讯作者：
Tsuzuki, Mikio
中科院分区：
文献类型：
--
作者：
Miyauchi, Hiroki;Okada, Katsuhiko;Tsuzuki, Mikio
附着式微藻培养系统或生物膜系统可以降低生物质回收的成本，是解决二氧化碳问题的一种有吸引力的方法。在这项研究中，我们开发了一种精确测量CO2在藻类生物膜上固定的方法，并优化了单细胞微藻小球藻的光合能力。用红外气体分析仪测量样品气体中的CO2浓度，并考虑样品气体与参比气体之间的H2O浓度差异进行校正。校正后的二氧化碳浓度与没有细胞的参比气体的浓度一致。利用所建立的方法，对附着在玻璃纤维膜过滤器上的小球藻的光合能力进行了表征。有趣的是，当细胞密度高达120 mg叶绿素m（-2）时，每个叶绿素的CO2固定率几乎与液体中相同。对滤光器的光依赖性与液体中非常相似，而光合速率在低CO2条件下比在液体中受到更明显的限制，这表明CO2是比光对滤光器更严重的限制因素。光合作用的细胞浓度依赖性和显微镜观察表明，光合作用仅由过滤器上层的几个细胞进行。为了改善二氧化碳的供应，固体表面变成了毛巾，尽管其光学透明度较低，但仍提高了光合速率。估计每个地区最大的二氧化碳捕集率超过110吨/公顷/年。这些发现表明，小球藻固体表面培养体系是一种很有前途的碳捕获体系，如果将固体表面转化为具有高光学透明度的立体结构，则可以进一步提高小球藻的碳捕获能力。
An attached microalgal culture system, or a biofilm system, which can reduce the cost of biomass recovery, is an attractive approach to solve the CO2 problem. In this study, we developed a method for precisely measuring CO2 fixation on algal biofilms, and optimized the photosynthetic capacity of a unicellular microalga, Chlorella. The CO2 concentration in the sample gas, measured with an infrared gas analyzer, was corrected by considering the difference in H2O concentration between the sample gas and the reference gas. The corrected CO2 concentration coincided with that of the reference gas, for which there were no cells. Using the established method, the photosynthetic capacity of Chlorella attached to a glass fiber membrane filter was characterized. Interestingly, the CO2 fixation rate per chlorophyll was almost the same as in liquid, at cell densities of up to 120 mg chlorophyll m(-2). The light-dependency on the filter was very similar to that in liquid, while the photosynthetic rate was more markedly limited under low CO2 conditions than in liquid, suggesting that CO2 is a more severe limiting factor than light on the filter. The cell concentration-dependency of photosynthesis and microscopic observations suggest that photosynthesis is only performed by cells in a few top layers on the filter. To improve the CO2 supply, the solid surface was changed to a towel, which increased the photosynthetic rate in spite of its low optical transparency. The maximum rate of CO2 capture per area was estimated to be over 110 tons ha(-1) year(-1). These findings suggest that the Chlorella solid-surface culture system is a promising system for carbon capture, and that it can be further improved if the solid surface is converted into a steric structure with a high optical transparency.