The effect of different concentrations of ammonium sulfate and pH extraction on the production of phycocyanin from Galdieria sp

The alternative blue pigment of phycocyanin sources other than Spirulina is Galdieria from Cyanidiales order. Galdieria sp. is unicellular red microalgae which naturally found in volcanic area with a high temperature and low pH (0.5–3). In this study, Galdieria sp. 009 has grown autotrophically in Allen medium and on different concentrations of ammonium sulfate. The growth and in vivo phycocyanin content were quantified in the cultures. Phycocyanin was extracted using a physical method with different extraction pH (3, 5, and 7). Highest specific phycocyanin content up to 100 mg g⁻¹ was observed in cell grown on Allen medium with two times ammonium sulfate concentration and extracted with pH 7. The different concentrations of ammonium sulfate used in the Allen medium impacted the yield of phycocyanin. Although extraction at pH 7 caused high phycocyanin content, the phycocyanin tends to have high thermostability (>60°C) and purity index at pH 5. The phycocyanin extracted from Galdieria sp.009 may potentially be an alternative blue food colorant beside Spirulina, as it has higher thermostability that Spirulina phycocyanin (>47°C).