藻类连续培养体系的构建与优化及其在产毒和无毒微囊藻竞争中的应用

ESTABLISHMENT AND OPTIMIZATION OF CONTINUOUS CULTURE SYSTEM AND APPLICATION IN THE COMPETITION BETWEEN TOXIC AND NON-TOXIC MICROCYSTIS

  • 摘要: 利用发酵罐加装外置环形光源构建藻类连续培养系统, 以产毒微囊藻PCC 7806及其无毒突变株PCC 7806 mcyB为培养材料, 通过对补料时间、接种密度和稀释率参数的优化, 获得最优培养条件, 并应用于产毒与无毒微囊藻的竞争实验中。通过优化得到连续培养的最优培养条件: 补料时间为第4天, 起始接种密度为4×106 cells/mL, 稀释率为0.15/d。在连续培养下, 光照为35 μmol/(m2·s)时, 以1﹕1的起始比例接种产毒与无毒微囊藻, 二者间的竞争会达到平衡, 并以无毒微囊藻占据优势, 且两者以不同的优势度长时间维持不变。在此基础上, 开展了不同光强对产毒与无毒微囊藻竞争影响的实验, 结果表明, 光强为35和80 μmol/(m2·s)时, 无毒株在连续培养中占据优势; 而光强为5和15 μmol/(m2·s)时, 无毒和产毒微囊藻维持起始接种比例不变。研究通过优化连续培养条件为室内藻类竞争实验提供了更为适宜的培养模式。

     

    Abstract: Continuous culture has become an important method to study the competition between toxic and non-toxic Microcystis. Under the continuous culture mode, the growth of Microcystis is not limited by nutrients and harmful metabolites, and its growth rate and metabolic activity are relatively constant. At this time, the growth of Microcystis is only controlled by single or multiple factors set by experimental conditions, and less influenced by other non-experimental factors. A continuous algal culture system was constructed by adding an external ring light source to the chemostat, and the optimal culture conditions were obtained by optimizing feeding time, inoculation density and dilution rate parameters, which were applied in the competition experiment between toxic Microcystis PCC 7806 and non-toxic Microcystis PCC 7806 mcyB. The optimal culture conditions for continuous culture were the 4th day for the feeding, the initial seeding density at 4×106 cells/mL and 0.15/d for the dilution rate. Under continuous culture, 1﹕1 ratio of toxic and non-toxic Microcystis inoculation were balanced at the beginning, with non-toxic Microcystis dominating later, and then remained unchanged for a long time with different degrees of dominance. On this basis, the influences of different light intensities on the competition between toxic and non-toxic Microcystis were carried out. The results showed that when the light intensities were 35 and 80 μmol/(m2·s), non-toxic strains dominated in continuous culture; while the light intensities were 5 and 15 μmol/(m2·s), the ratio of non-toxic and toxic Microcystis remained unchanged. The optimization of algal continuous culture system provides a suitable culture mode for indoor algal competition test. Besides, the influence of light intensity on toxic and non-toxic Microcystis provides technical support for exploring the competitive succession mechanism.

     

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