Hyper accumulation of C-phycocyanin by Arthrospira platensis in succinate-fed pulse cultivation mode
Hyper accumulation of C-phycocyanin by Arthrospira platensis in succinate-fed pulse cultivation mode
Rezvan Mousavi-Nadushan,1,*Arman Araji,2
1. Department of Marine Science, Faculty of Natural Resources and Environment, Tehran North Branch, Islamic Azad University, Tehran, Iran. 2. Department of Marine Science, Faculty of Natural Resources and Environment, Tehran North Branch, Islamic Azad University, Tehran, Iran.
Introduction: The A. platensis is a multicellular, filiform, helical-shaped, and photosynthetic blue-green prokaryotic microalgae. It is greater than most species and is simply/quickly ingested and absorbed in the human body owing to the lack of cellulose in its cell wall. The A. platensis is one of the most fascinating microalgae, which can be applied for the manufacturing of functional foods, cosmetics, antioxidant colorants, neutaceiticals, supplements, medicine, due to their relatively high contents of vitamins, minerals with many health profits (counting antitumor, reductant inhibitor, antiviral, antiphlogistic effects, etc.) as well as positive influences against mal-nutrition, fatness, diabetes, anemia, etc. without any undesirable secondary effect on human fitness.
A. platensis is a protein-rich cyanobacterium (60–70% (w/w)) and a promising source for c-phycocyanin (47% of the total proteins). It has double colorants including phycobiliproteins; allophycocyanin (APC) and c-phycocyanin (CPC), which originates 15–20% of dry cell mass. Consistent with Future Market Insights, c-phycocyanin worldwide market worth will each a value surpassing $232.9 million, by the end of 2025.
Moreover, it has been reported that biomass production of A. platensis in the open pond was usually lower than 0.8 g L−1 and contained only around 7% phycocyanin content. Several studies have tried to improve A. platensis biomass and phycocyanin yield with cultivation governing, such as pre-harvesting, nitrate-fed cultivation. Glutamate and succinyl–Coenzyme A are amongst the transitional metabolites in the biosynthesis of tetrapyrroles such as phycobilin and chlorophyll, in algal and cyanobacteria cells. In other words, the sodium glutamate and succinic acid are substrates that could activate the phycocyanin increase as consequence of metabolic pressure.
Methods: The Arthrospira (Spirulina) platensis were fed batch cultured in Zarrouk medium. The initial nitrate concentration was 2500 mg L−1, the first pulse day was 8th day of cultivation period, and the addition concentration of sodium glutamate and succinic acid was 5 mmol L−1/ 7.5 mmol L−1, and the second pulse day was 12th day of cultivation period, for both treatments.
Results: The maximal Allophycocyanin and Phycocyanin production was obtained for pulse day succinic acid addition at 19th day of cultivation (p˂0.05). The high Allophycocyanin concentrations (0.2 And 0.31 mg mL−1) were obtained for sodium glutamate and succinic acid pulse day addition, respectively, while phycocyanin concentrations reached to 0.14 and 0.23 mg mL−1.
Conclusion: Succinic acid is a C4-dicarboxylic acid produced as a key intermediate of the tricarboxylic acid (TCA) and tetrapyrroles biosynthesis. As a widely investigated high-value chemical, it has numerous applications in the fields of agriculture/aquaculture, green solvents and pharmaceuticals. Several studies indicated that TCA cycle intermediates were able to function as chemical stimulators for motivating zeaxanthin accumulation in Flavobacterium multivorum. Besides, exogenous Succinic acid improved stimulated Larix olgensis cultivating growth by effective photosynthesis and antioxidative properties.
In the present study, the high Allophycocyanin/phycocyanin concentrations ((0.2 And 0.31 mg mL−1) / (0.14 and 0.23) were obtained at 19th day of cultivation, for pulse fed succinic acid and sodium glutamate, respectively. In contrast, in another study Allophycocyanin accumulation of 0.116 and 0.114 mg mL−1 was obtained for sodium glutamate and succinic acid cultivation, respectively. Once more, applying sodium glutamate / Succinic acid combined with nitrate feeding strategy, they obtained phycocyanin concentrations of 0.212 and 0.234 mg mL−1.
Based on our results succinate pulsed cultures exhibited higher Allophycocyanin and Phycocyanin accumulation compared to Glutamate pulse culture. These data evidenced the choice of the succinic acid as intermediate precursor source for the cultivation of A. platensis. Therefore, addition of substrates in the fed batch (pulse day) regime has boosted phycocyanin content, then again succinic acid was found to be the best substrate for Allophycocyanin hyperaccumulation as well as high phycocyanin production.