The Preliminary Studies On The Relationship Of Phycoerythrin And EPA In Porphyridium Cruentum

Porphyridium cruentum is the only kind of unicellular red alga found by now. It can synthesize some bioactive substances such as phycoerythrin, polyunsaturated fatty acids (EPA, AA, et al) and exopolysaccharide. Phycoerythrin and EPA has very high practical value to human beings, so the study about Porphyridium cruentum is of great significance for it’s development and utilization.This paper starting with different phycoerythrin and EPA content under different environmental conditions, we explored the relationship between EPA synthesis and phycoerythrin, and one step forward, the relationship between EPA’s synthesis and chloroplast state. We hoped to find a certain situation in which both field can be improved, and established the theoretical foundation for it’s practical application in the future.The results of this study are summarized as follows:1. It has optimized the best growth conditions for Porphyridium cruentum. It’s been found that8mM/L N concentration, light intensity of4000-6000LX.15-30‰salinity made up of the best growth conditions for Porphyridium cruentum. In this environment, the yields of antioxidant enzymes (SOD, POD) and molecular signal NO were relatively low, which further proved that aforementioned conditions were conducive to microalgae growth.2. It has measured phycoerythrin content under different conditions and found that phycoerythrin content would increase with N concentration increasing within a certain range (0-8mM/L). But N concentration too high didn’t have such an effect. In addition, the content of phycoerythrin was influenced by light intensity. The weaker light intensity was, the higher the content was. NaCl concentration within a certain range (15-90‰) also had a great influence on phycoerythrin accumulation. Phycoerythrin content would decrease as NaCl concentration increased. But low salinity would also slow down the accumulation.3. It has measured PUFAs content by GC under different conditions and found that the variation trend of EPA content was consistent with phycoerythrin’s. It increased with N concentration rising within a certain range (0-8mM/L). But N with a too high concentration could not effectively help production of EPA. In addition, the weaker the light intensity was, the higher the content was. Within a certain range of NaCl concentration (15-90‰), EPA content would decrease with NaCl concentration increasing. But salinity too low would also inhibit the accumulation. AA and LA, have variation trends contrary to EPA, with only NaCl concentration group as an exception.4. It’s been found that8mM/L N concentration, light intensity of1000LX,15‰NaCl concentration made up of the best accumulation conditions for phycoerythrin and EPA in Porphyridium cruentum. And it may be a conclusion:a certain positive correlation relationship between phycoerythrin and EPA may exsist. and the change of phycoerythrin content is the main reason why EPA content changes.5. We cloned part cDNA sequence of delta12and delta15desaturation enzyme gene using RT-PCR. The two cDNA fragments were417,480bp in length. However,after sequence alignment, no similar desaturation enzyme gene sequence has been found in NCBI.