光质对工程聚球藻7002生长及psbA启动子的调控

Effects of light quality on cell growth and psbA promoter of engineered Synechococcus sp. PCC7002

摘要:

工程聚球藻的psbA基因及其所用载体的启动子PpsbA均受光质调控，利用该机制可通过光质调控提高聚球藻的光合效率及其外源基因表达率。以转vp28基因聚球藻7002为实验材料，通过优化光强、温度及pH，解除光限制因素并提高光能利用率。通过改变白光、红光及蓝光的比例，调控光质组成及单色光的光强，检测细胞生长、外源基因的表达及psbA基因的转录。研究结果表明：高比例蓝光下，vp28基因的表达率达到2.4%，是纯白光下的3倍，重组蛋白VP28的积累量提高至2倍。高比例红光抑制了psbAII、psbAIII基因及外源基因的表达，但促使生物量在3 d内突破1.5 g/L。本研究为蓝藻的生物制药和工程蓝藻代谢产物的产业化提供了理论基础。

Abstract:

Light quality can regulate both psbA genes and vector promoter psbA of the engineered Synechococcus. Through light regulation, we tried to improve yield of the recombinant protein for vp28 gene-expressed Synechococcus sp. PCC7002. To drive photon-capturing efficiently, three limiting factors (irradiance, temperature and pH) were optimized by measuring net photosynthesis. High cell density cultures were performed with variant ratios of white, red and blue light in a 5-L photo-bioreactor. Yields of biomass, expressions of vp28 and transcription levels of psbA were compared. High ratio blue light-induced vp28 transcription had tripled and the relative accumulation of VP28 protein was doubled. The relative expressions of psbAII and psbAIII had positive correlations with higher ratio of blue light, not the red light. With high ratio red light inducing, dry biomass reached 1.5 g/L in three days. Therefore, we speculated that red light accelerated biomass accumulation of the transgenic strain and blue light promoted transcription for PpsbA and psbA. These results provided useful information for mass production of cyanobacteria and its secondary metabolites.