Optimization And Scale Up Of Galdieria Sulphuraria 074G Cultivation For Efficient Production Of Phycocyanin

Phycocyanin is a compound of protein and pigment which is mainly extracted from Spirulina and has broad application prospects in the healthcare field.Compared with Spirulina,the red algae Galdieria sulphuraria has the advantage of heterotrophic culture,with high cell growth rate and high productivity of phycocyanin.Therefore,there are more and more studies on the accumulation of phycocyanin by Galdieria sulphuraria 074G.A cultivation model named "Sequential Heterotrophy-Dilution-Photoinduction" of Galldieria sulphuraria 074G was preliminarily established in author's laboratory.The production of phycocyanin by this cultivation strategy has the advantages of high yield and high quality.However,it's still limited to research indoors and small-scale.Therefore,it is of great practical significance to propel study in the high-efficiency,large-scale cultivation of G.sulphuraria 074G.In this study,the heterotrophic cultivation and photoinduction of G.sulphuraria 074G with the cultivation strategy "Sequential Heterotrophy-Dilution-Photoinduction" are optimized and enlarged.The main conclusions are as follows:(1)The effect of nutrient elements on heterotrophic cultivation of G.sulphuraria 074G showed:The effects of C/N ratio on heterotrophic cultivation of G sulphuraria 074G is related to the concentration of carbon source.At low glucose concentrations,there is an optimal C/N ratio.With the increase of carbon source concentration,the effect of different C/N ratio on cell growth is gradually minimized.The effects of nine metal ions on heterotrophic cultivation of G.sulphuraria 074G were investigated.The optimal concentration of Mg2+and Zn2+are 300 mg/L and 0.88 mg/L respectively.Finally,the metal ion concentration in heterotrophic medium was optimized,the cell density was increased by 14.5%than in the initially medium.(2)About G sulphuraria 074G high density heterotrophic cultivation.Establishment and optimization of heterotrophic cultivation of G.sulphuraria 074G in 5L fermenters had found that the C/N ratio was the restrictive factor in heterotrophic cultivation of G.sulphuraria 074G.The heterotrophic cultivation of G.sulphuraria 074G was enlarged in a 50L fermentor and the final cell density reached 145.23 g/L.(3)About photoinduction of G.sulphuraria 074G with high productivity of phycocyanin.Under the light-dark cycle(12h:12h),the optimum temperature for daytime induction of G.sulphuraria 074G is 46?,the optimum temperature at night induction is 40?.The continuous inlet of CO2 and mixing in the reactor at night facilitates photoinduction of G.sulphuraria 074G.Under indoor condition and outdoor condition,contrastive studies of photobioreactor evaluation and preliminary amplification on photoinduction of G.sulphuraria 074G in 1L column photoreactor,3L flat plate bioreactor and 15L flat plate bioreactor were carried out.(4)About photobioreactor evaluation and preliminary amplification of photoinduction of G.sulphuraria 074G.Cornet light attenuation model of algae G.sulphuraria 074G with good applicability was established with light absorption coefficient Ea=0.0126 m2/g and light scattering coefficient Es=2.5628 g/L.Under indoor condition and outdoor condition,contrastive studies of photobioreactor evaluation and preliminary amplification on photoinduction of G.sulphuraria 074G in 1L column photoreactor,3L flat plate bioreactor and 15L flat plate bioreactor were carried out.Studies have shown that the key parameter of photoinduction cultivation is the volume-averaged light intensity in the initial phase of photoinduction of heterotrophic cells,and the result of photoinducion of of G.sulphuraria 074G is best when the value is around 600 ?mol/(m2·s)during photoinduction.Photoinducion of G.sulphuraria 074G was preliminary enlarged in 1.35m2 raceway pond,the volume-averaged light intensityIavV is 543 ?mol/(m2·s),and the productivity of phycocyanin was 17.25 mg/L/d.