不同营养方式下小球藻生长与光合作用的变化

Variation of Growth and Photosynthesis in Chlorella sorokiniana Under Different Trophic Modes

【目的】研究小球藻在自养条件下和以乙酸为碳源的异养、混养条件下生长以及光合作用的变化。【方法】以小球藻Chlorella sorokiniana为研究对象，通过测定OD550和光系统Ⅱ（PSⅡ）叶绿素荧光研究其生长情况和光合作用的变化。【结果】小球藻在初始接种浓度为5×10^6个／mL的条件下，异养和混养的生长速度显著快于自养，到达稳定期仅需1．5d，而自养生长需要9d；叶绿素荧光参数自养大于混养，而混养又大于异养，有效光量子产量混养比自养降低21．5％，异养比自养降低98．1％；混养的Rubisco酶基因mRNA表达量最高，分别是异养和自养的3．2倍和1．8倍。【结论】小球藻在混养条件下光系统仅受到微弱抑制，生长速度和最高细胞密度均高于其它营养方式，适合规模化培养。

【Objective】The variation of growth and photosynthesis of microalgae was studied and compared under autotrophic condition and hetero-and mixotrop hic conditions with acetate as carbon source.【Methods】With Chlorella sorokiniana as material,the changes of growth and photosynthesis were reflected by determining the OD_(550) and the chlorophyll fluorescence from photosystem Ⅱ(PS Ⅱ).【Results】The growth rates of hetero-and mixotrophic conditions were significantly higher than that of autotrophic condition.It was only 1.5d for cells reaching stationary phase under hetero-and mixotrophic conditions,but 9d for cells under autotrophic condition.The parameters of chlorophyll fluorescence under autotrophic condition were significantly higher than that under hetero-and mixotrophic conditions,and that under mixotrophic condition were significantly higher than that under heterotrophic condition.The effective PS Ⅱquantum yield under mixo-and heterotrophic condition was reduced 21.5% and 98.1%,respectively,compared with that of autotrophic condition.The mRNA expression of Rubisco gene under mixotrophic condition were highest,and 3.2-fold and 1.8-fold of that under hetero-and autotrophic conditions,respectively.【Conclusion】The photosystems of C hlorellaunder mixotro-phic condition only slightly inhibited.In addition,the growth rate and maximal cell density under mixotrophic condition were higher than other conditions.Therefore,mixotrophic growth mode is suitable for large-scale cultivation.