Optimization Of C-phycocyanin Photoproduction In Spirulina Platensis And Extraction Conditions

In recent years, many marine organisms, especially a lot of algaes were found with the intensive study of marine biology. Blue-green algae Spirulina platensis is gaining more and more attentions as a nutraceutical and source of potential Pharmaceuticals. The biological and pharmaceutical properties of Spirulina sp. were mainly attributed to C-phycocyanin (C-PC). C-phycocyanin, a non-toxic water-soluble fluorescent protein pigment, is one of the major components of Spirulina platensis. Some studies have demonstrated the antioxidant, antimutagenic, antiviral, anticancer, anti-allergic, immune enhancing, hepato-protective, blood vessel relaxing and blood lip id-lowering effects of C-phycocyanin.The initial culture conditions were described as follows:nitrogen source30mM NaNO3, carbon source2.5%CO2(flow rate0.2vvm) and temperature28℃. Basing on a good performing photobioreactor and the Zarrouk medium, the effects of different light intensity and inoculum size on cell growth and C-phycocyanin photoproduction of Spirulina platensis were investigated. The results showed that the optimal light intensity was300μmol/m2/s and the optimal inoculum size was0.24g/L. Under this condition, the biomass productivity reached576.3mg/L/d and the C-phycocyanin productivity reached77.4mg/L/d respectively.Secondly, two strategies were used to culture the microalgae after the determination of the optimum light intensity and inoculum size. The stepwise increasing light intensity strategy could be effective in promoting cell growth of the microalgae, raising the biomass productivity from576.3mg/L/d to709.4mg/L/d. However, this culture strategy would reduce the C-phycocyanin content in the last phase of fermentation, the fed-batch strategy could improve it effectively. Different components (nitrate or medium) and different concentration (5mM or10mM) of the nitrogen were fedding in culture process. When fedding the medium of the same concentration with5mM nitrate, the highest C-phycocyanin productivity reached94.8mg/L/d and increased22.5%in comparison with the batch culture.Finally, on the basis of single factor test, the Box-Behnken response surface design and the Design Expert8.0.6software were utilized to optimize the extraction process of C-phycocyanin. The results of the optimization were described as follows: so lid-to-liquid ratio2.0mg/mL, extraction time37.1h and extraction temperature25.6℃. The extraction yield of C-phycocyanin was13.66%under the optimal conditions, which was about32.8%higher than that of non-optimized conditions and perfectly matched the predicted value (13.72%).This article greatly enhanced the cell growth and C-phycocyanin photoproduction of Spirulina platensis and provided a guidance for its industrial production.