果糖-1,6-二磷酸醛缩酶和丙糖磷酸异构酶共表达对蓝藻光合作用效率的影响

以转高等植物ALD和TPI基因的鱼腥藻 7120为对象 ,研究了ALD和TPI两个酶表达量对细胞光合固碳效率的影响。考察了初始pH、NaHCO₃浓度和CO₂浓度对转基因藻和野生藻生长、光合活性及无机碳亲和力的影响。结果表明 ,转基因藻在较高碳源浓度下 ,其生长速率和光合放氧活性比野生藻有显著的提高 ,并且可以比野生藻耐受更高的pH。在含有2%CO₂的空气中 ,转基因藻对外源无机碳的亲和力比野生藻提高了4.06倍.

Regulation on Photosynthetic Efficiency of Anabaena sp.PCC7120 by the Co-expression of two Higher Plants Genes ALD and TPI

Triosephosphate isomerase (EC 5.3.1.1, TPI) and fructose-1, 6-bisphosphate aldolase (EC 4.1.2.13, ALD) were key enzymes in the Calvin cycle which plays a significant role in regulating the carbon flux through the cycle. For the regulation of photosynthesis at gene level, the genes encoding ALD and TPI were transferred into filamentous, heterocystour cyanobacterium Anabaena sp. PCC7120, which were from spinach and rice, respectively. The aim of this work was to explore the possibility that photosynthetic carbon fixation in cyanobacteria may be enhanced by increasing the cellular ALD and TPI available for the regeneration of RuBP. In this study, cells were grown in the BG11 medium supplemented with different concentrations of NaHCO 3 or CO 2. The growth parameters, photosynthesis and the apparent photosynthetic affinity for external inorganic carbon (Ci) under different conditions were measured and compared between transgenic and wild type cells. Transgenic cells grew better than wild type cells under higher initial pH. Both cell growth and photosynthesis activities were improved under elevated CO 2, especially for transgenic cells. Under 2% CO 2 enriched air, the apparent photosynthetic affinity for external Ci for transgenic cells was 4.06 times higher than that for wild type cells. These data indicated that the overexpress of foreign ALD and TPI affected the photosynthetic carbon fixation process through the accelerating of carbon flux.