RESUMO
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.
Assuntos
Regulação Bacteriana da Expressão Gênica , Luz , Complexo de Proteína do Fotossistema II , Genética , Regiões Promotoras Genéticas , Synechococcus , Genética , Efeitos da RadiaçãoRESUMO
Carbon (neutral) based renewable liquid biofuels are alternative to petroleum derived transport fuels that contribute to global warming and are of a limited availability. Microalgae based biofuels are considered as promising source of energy. Lyngbya sp. and Synechococcus sp. were studied for the possibility of biodiesel production in different media such as ASNIII, sea water enrichment medium and BG11. The sea water enrichment medium was found superior in enhancing the growth rate of these microalgae. Nitrogen depletion has less effect in total chlorophyll a content, at the same time the lipid content was increased in both Lyngbya sp. and Synechococcus sp. by 1.4 and 1.2 % respectively. Increase in salinity from 0.5-1.0 M also showed an increase in the lipid content to 2.0 and 0.8 % in these strains; but a salinity of 1.5 M has a total inhibitory effect in the growth. The total biomass yield was comparatively higher in tubular LED photobioreactor than the fluorescent flat plated photobioreactor. Lipid extraction was obtained maximum at 60 ºC in 1:10 sample: solvent ratio. GC-MS analysis of biodiesel showed high content of polyunsaturated fatty acids (PUFA; 4.86 %) than saturated fatty acid (SFA; 4.10 %). Biodiesel production was found maximum in Synechococcus sp. than Lyngbya sp. The viscosity of the biodiesel was closely related to conventional diesel. The results strongly suggest that marine microalgae could be used as a renewable energy source for biodiesel production.
Assuntos
Biocombustíveis , Biomassa , Reatores Biológicos , Carbono/química , Clorofila/metabolismo , Cianobactérias/metabolismo , Fontes Geradoras de Energia/economia , Desenho de Equipamento , Ésteres/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Lipídeos/química , Microalgas , Nitrogênio/metabolismo , Fotoquímica/métodos , Solventes/química , Synechococcus/metabolismo , Triglicerídeos/química , ViscosidadeRESUMO
Time course of carotenoid and membrane lipid variation during high light (HL) acclimation (about 85 μmol m−2 s−1), after transfer from low light (LL) (5–10 μmol m−2 s−1), was determined in a marine Synechococcus strain. Highperformance liquid chromatography (HPLC) coupled to diode array detector (DAD) or electrospray ionization mass spectrometry (ESI-MS) was used for compound separation and detection. Myxoxanthophyll rose within a time interval of 8 h to 24 h after the onset of exposure to HL. β-carotene content started to decrease after 4 h of the onset of exposure to HL. Zeaxanthin content rose with exposure to HL, but it was only significant after 24 h of exposure. Carotenoid changes are in agreement with a coordinated activity of the enzymes of the myxoxanthophyll biosynthetic pathway, with no rate-limiting intermediate steps. Lipid analysis showed all species with a C18:3/C16:0 composition increased their content, the changes of PG(18:3/16:0) and MGDG(18:3/16:0) being primarily significant. Major lipid changes were also found to occur within 24 h. These changes might suggest reduction and reorganization of the thylakoid membrane structure. Hypotheses are also drawn on the role played by lipid molecule shape and their possible effect in membrane fluidity and protein accommodation.
RESUMO
Objective To study the biological activities of Synechococcus sp.PCC7942 with trans-mutated hCu,Zn-SOD-gene.Methods Synechococcus sp.PCC7942 with trans-mutated hCu,Zn-SOD were administered orally for 20d to mice,then the activities of glutathione peroxidase(GSH-Px),catalase(CAT),superoxide dismutase(SOD) and the content of malondialdehyde(MDA) were determined.Results The activities of GSHPx in serum and the activities of CAT in blood increased obviously;the activity of SOD in serum and liver increased markedly;the content of MDA in serum and liver decreased obviously.Conclusion Synechococcus sp.PCC7942 with trans-mutated hCu,Zn-SOD-gene had obvious antioxidant effect in vivo.
RESUMO
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.