碳酸钙中的碳能被微藻利用吗

碳酸钙中的碳能否被微藻利用这一问题一直处于争论中。本文在开放与隔离空气CO2环境下用含有碳酸钙粉末和不同浓度乙酰唑胺的培养液培养衣藻和小球藻。通过双向同位素示踪技术,定量描述出不同条件下微藻对碳酸钙碳源的利用份额。在隔离空气CO2的环境下,微藻对碳酸钙碳源的利用份额明显大于开放环境下。在开放环境下,随着培养液中乙酰唑胺浓度增加,生物量减少,微藻对固有无机碳源的利用份额减少,对碳酸钙碳源的利用份额增加。在隔离空气CO2的环境下,随着培养液中乙酰唑胺浓度增加,微藻生物量增加,衣藻对固有无机碳源的利用份额增加,对碳酸钙碳源的利用份额减少,而小球藻反之。微藻主要是通过利用碳酸钙溶蚀的可溶性无机碳(DIC)这种间接方式来利用碳酸钙碳源。而外界大气CO2浓度和胞外碳酸酐酶是影响碳酸钙溶解的重要因素,因此其也明显的影响着微藻对碳酸钙碳源的利用。

Can Carbon in Calcium Carbonate Be Utilized by Microalgae

The issue whether the carbon in calcium carbonate can be utilized by microalgaeis under debate. In the open or CO₂-isolated environment, Chlamydomonas reinhardtii and Chlorella pyrenoidosa were cultured in the medium containing calcium carbonate powder under different concentrations of acetazolamide. Using the bidirectional isotope tracer labeling technique, we quantified the proportion of calcium carbonate-carbon source utilized by microalgae at different conditions. The proportion of calcium carbonate-carbon source utilized by microalgae in the CO₂-isolated environment was greater than that in the open environment. In the open environment, the algal biomass decreased with increasing concentration of acetazolamide in the medium. Meanwhile, the proportion of the inherent carbon source utilized by microalgae increased, and that of calcium carbonate-carbon source accordingly decreased. However, in the CO₂-isolated environment the microalgae''s biomass increased with increasing concentration of acetazolamide in the medium. Meanwhile, the proportion of the inherent carbon source utilized by Chlamydomonas reinhardtii decreased, and that of calcium carbonate-carbon source accordingly increased. This situation is contrary to Chlorella pyrenoidosa. Microalgae utilized calcium carbonate-carbon source from the dissolution of calcium carbonate to dissolved inorganic carbon in an indirect way. The atmospheric CO₂ concentrations and extracellular carbonic anhydrase were the important factors that influenced the dissolution of calcium carbonate, and they also obviously influenced calcium carbonate-carbon source utilized by microalgae.