葡萄糖对小球藻(Chloralla sp. HN08)光合作用和生长的影响

Effects of glucose on photosynthesis and growth of Chloralla sp. HN08 cells

【目的】探讨葡萄糖作为外加碳源对热带海洋小球藻(Chloralla sp.HN08)生物质生产和脂、光合色素、碳水化合物及可溶性蛋白等细胞主要成份含量的影响。【方法】分析比较小球藻HN08在光合自养和兼养(添加10 g/L葡萄糖)2种营养方式下的生长速率、细胞密度、光合放氧速率、油脂相对含量,以及可溶性总糖、淀粉和可溶性蛋白的含量。【结果】结果表明,在光照条件下葡萄糖(10 g/L)能促进小球藻(Chloralla sp.HN08)生长,提高细胞终密度,而异养条件下藻细胞逐渐衰亡。兼养条件下,细胞相对生长速率及细胞终密度分别是自养条件下的6.8倍和1.3倍。兼养藻细胞中可溶性糖、淀粉、油脂含量显著高于(P<0.05)光合自养细胞,然而可溶性蛋白质和光合色素含量显著低于(P<0.05)光合自养细胞。添加葡萄糖的小球藻液的光饱和点和呼吸速率均高于光自养条件下的细胞,但2种培养条件下藻液的净光合速率无显著差异(P>0.05)。【结论】光照条件下,添加葡萄糖可显著提高小球藻HN08相对生长速率和细胞终密度,促进油脂与淀粉的积累。

[Objective] To study the potential of using glucose as carbon source to produce microalgae biomass and biochemical components, such as photosynthetic pigments, lipids, carbohydrates and proteins by tropical marine microalgae Chloralla sp. HN08. [Methods] We compared the growth characteristics of Chloralla sp. HN08 cells under photoautotrophic and mixotrophic（10 g/L glucose was added into the medium） conditions. The photosynthesis, specific growth rates, cell densities, and the content of cell＇s major components including lipids, starch, soluble sugar, and soluble protein were determined and compared. [Results] Glucose（10 g/L in medium） could promote Chlorella growth and increase the final cell density under light condition. However, cells declined gradually under heterotrophic condition. Under mixotrophic condition, the specific growth rate and the final cell density were 6.8 and 1.3 times as that of cells under photoautotrophic condition, respectively. The content of soluble sugar, starch, and lipids in mixotrophic cells was also significantly higher（P〈0.05） than that in photoautotrophic cells. However, the content of soluble protein and photosynthetic pigments of mixotrophic cells was significantly lower（P〈0.05） than that of autotrophic cells. Algae culture with glucose addition showed a higher light saturation as well as respiration rate. No significant difference in net photosynthesis rate was found between autotrophic and mixotrophic cultures（P〉0.05）. [Conclusion] Under light condition, glucose as a carbon source can promote lipids and starch accumulation, as well as biomass production.