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.
Subject(s)
Gene Expression Regulation, Bacterial , Light , Photosystem II Protein Complex , Genetics , Promoter Regions, Genetic , Synechococcus , Genetics , Radiation EffectsABSTRACT
The growth predominance and culturing potential of transgenic Synechococcus sp.PCC 7002 with mouse metallothionein-Igene are characterized and expatiated by room temperature absorption spectra,photosynthetic oxygen evolution rate,growth kinetic parameters.The results show that the spectral absorption,maximum net photosynthetic rate and saturated light intensity of transgenic Synechococcus sp.PCC 7002 are higher than wild strain,whereas its the respiration rate and compensating light intensity are lower than wild strain.The transgenic cells exhibit a higher growth rate,and the maximum cell concentration is 1.74 times higher than wild ones when cultured in shaking flask.The air lift photobioreactor is suitable for bringing its growth potential into play.