Thermosynechococcus Isolated from the Hot Spring in Northern Thailand as a Source of Thermostable Phycocyanin

Phycocyanin (PC), a blue pigment, is widely used in food and cosmetic as a colorant. Most of commercial phycocyanin are extracted from a cyanobacterium, Arthrospira platensis. Nonetheless, the applications of natural blue from A. platensis in food and other products are limited due to the denaturation caused by heating process. Therefore, alternative sources of phycocyanin which has the thermostable property are requisite. Thermosynechococcus sp. FA-CM-4201 isolated from hot springs in Northern Thailand is an attractive cyanobacterium because it naturally grows at temperature of 76 ^oC. Therefore, the purpose of this study is to investigate the thermostable property of extracted PC from Thermosynechococcus sp. FA-CM-4201 (FACM4201-PC). The FACM4201-PC was extracted using phosphate buffer and further purified using a process of microfiltration and ultrafiltration. After that, the purified FACM4201-PC was freeze- dried. Thermostable stability of FACM4201-PC in the different pH buffer solutions (pH 5, 6, and 7) at temperatures ranging from 40 to 90 ^oC was compared with PC from A. platensis (commercial-PC). The results of the heat stability test revealed that the FACM4201-PC was more stable than the commercial-PC. At 70 °C for 30 minutes, the FACM4201-PC concentrations in buffer pH 5, 6, and 7 remained over 90% of the initial values, whereas the commercial-PC degraded more than 50% in all solutions. Furthermore, after 7 days of storage at 50°C, the stability of the FACM4201-PC in all buffer solutions was greater than that of the commercial-PC. The results obtained suggested that the FACM4201-PC is a promising thermostable phycocyanin with a great potential for high temperature applications.