两株绿藻响应CO2浓度变化的生长和生理特性的研究

THE GROWTH AND PHYSIOLOGICAL RESPONSES OF TWO GREEN ALGAE TO THE CHANGE OF CO2 CONCENTRATION

  • 摘要: 以小球藻FACHB-1580和栅藻FACHB-1618为研究对象, 比较了两株绿藻在0.04% CO2、5% CO2和20% CO2 (v/v)三种通气培养条件下的生长和生理特性的响应, 试图阐述与无机碳利用相关生理参数和微藻利用CO2能力的关系。结果表明, 两株绿藻均能高效利用CO2, 在5%(v/v)条件下均表现出最大生物量积累、最大比生长速率和最大二氧化碳固定速率。小球藻FACHB-1580和栅藻FACHB-1618最大生物量分别为3.5和5.4 g/L, 分别是0.04% CO2 (v/v)条件的1.41和1.46倍。在高达20% CO2 (v/v)条件下, 两株绿藻的生物量均显著高于空气组(P<0.05)。随着CO2浓度的增加, 两株绿藻的无机碳亲和力、胞内和胞外CA活性、初始Rubisco活性, 及Rubisco活化度均有下降趋势, 总的Rubisco活性变化不明显。另外, 小球藻FACHB-1580存在较高的胞外和胞内CA活性; 而栅藻FACHB-1618胞外CA活性几乎为零, 胞内CA活性显著低于小球藻FACHB-1580。由此推测, 小球藻FACHB-1580能同时吸收介质中的\rmHCO_3^ - 和CO2, 其胞内CA催化胞内\rmHCO_3^ - 快速转化为CO2, 从而为Rubisco提供充足的CO2来源; 而栅藻FACHB-1618主要吸收介质中的CO2, 其胞内CA活性较低, 推测其通过提高胞内CA含量, 或增强Rubisco对CO2的亲和力等促进光合固碳作用。

     

    Abstract: Selection of microalgae strains that are capable of utilizing high concentration of CO2 is essential for industrial application. At present, the microalgae research mainly focus on the biomass, bioactive products and recovery properties, rather than physiological properties. The influence of different CO2 concentrations, including air, 5% CO2 and 20% CO2 (v/v), on the growth and physiological properties of Chlorella sp. FACHB-1580 and Scenedesmus sp. FACHB-1618 were studied. The goal was to clarify the relationship between the physiological properties and the CO2 utilizing capacity. Results showed that both strains were capable to use high concentration of CO2 and had the maximum biomass accumulation, specific growth rate and CO2 fixation rate under 5% CO2 (v/v) culture condition. The maximum biomass was 3.5 g/L in Chlorella sp. FACHB-1580 and 5.4 g/L in Scenedesmus sp. FACHB-1618 which was 1.41 and 1.46 times higher in comparison with the control (air) group, respectively. Both strains had higher biomass under 20% CO2 (v/v) condition than that in the air group (P < 0.05). With the increasing supply of CO2, the affinity of inorganic carbon, the activity of intracellular (CAint) and extracellular (CAext) carbonic anhydrase, as well as the initial activity and activation rate of Rubisco declined in both strains. However, there was no significant difference in the total Rubisco activity across time. In addition, Chlorella sp. FACHB-1580 had significantly higher levels of CAint and CAext activities. By contrast, Scenedesmus sp. FACHB-1618 had very poor CAint and CAext activities and were not detectable, indicating these two strains differed significantly in the utility of inorganic carbon. It was speculated that Chlorella sp. FACHB-1580 can absorb both CO2 and \rmHCO_3^ - whereas the Scenedesmus sp. FACHB-1618 tends to only absorb CO2. Chlorella sp. FACHB-1580 may obtain its abundant CO2 for Rubisco via high CAint activity; for Scenedesmus sp. FACHB-1618, due to its lower CAint activity, it may increase the amount of CA protein, or higher carboxylase affinity for CO2 to promote the reactions of photosynthesis.

     

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