Optimization Of Culture Conditions For Porphyridium Cruentum In The Flat Plate Photobioreactors

Porphyridium cruentum,a kind of the marine microalgae, attracts increasing interest for it can synthsis some valuable compounds such as phycoerythrin, sulfated exopolysaccharides and polyunsaturated fatty acids. To investigate the effect of culture conditions on the growth and some metabolites production of P. cruentum, the light attenuation model, the some key growth parameters and the optimal culture process were researched in the flat plate photobioreactor. The results were showed as follow.In the flask cultures, the productivity of biomass and extracellular polysaccharides of P. cruentum arrived to the biggest value when the original pH was 7.5. When the vaccination was 10%, the largest biomass was harvested; however, the largest extracellular polysaccharides of 460mg/ and 475mg/L were obtained when vaccination was 10% and 20%, respectively. And the nitro nitrogen could increase the productivity of the biomass and accumulation of extracellular polysaccharides of P. cruentum.The optical attenuation equation and the average light intensity calculation equation of P. cruentum were obtained in the flat plate photobioreactors. And some important growth parameters were determinated such as DO, pH, optical attenuator, the consumption of phosphorus and nitrogen in the different light-path flat plate photobioreactors. The results showed that the photobioreactor of small light-path (30 mm) could improved the light utilization efficiency, and a high of cells density and polysaccharide production could be obtained.To improve the cultural density and polysaccharide production, the cultural conditions of P.cruentum were optimized by the method of uniform design in flat plate photobioreactors. And the relationship between the renewal rate and the total harvest of biomass and polysaccharides was studied under the cultural modle of semi-continuous culture. The results showed that the total productivity of biomass reached to 69.5 g under the conditions of NaNO3 1.504 g/L, 32.93% renewal rate, and 1d renewal cycle; and the total harvest of polysaccharides amounted to 17.6 g with the conditions of NaNO3 3.5 g/L, 26.83% renewal rate and 2.9d renewal cycle.