Production of Thermostable phycocyanin in Spirulina

This study focuses on enhancing the thermal stability of phycocyanin, a valuable blue pigment from <i>Spirulina</i>, widely used as a natural dye and protein supplement. While phycocyanin degrades at temperatures above 45–50ºC, thermostable variants exist in thermophilic microalgae such as <i>Galdieria sulphuraria</i>, though these strains are difficult and costly to cultivate. To overcome this, thermostable phycocyanin genes from <i>G. sulphuraria</i> were cloned and introduced into commercial <i>Spirulina</i> using Agrobacterium-mediated transformation. Validation confirmed successful gene integration and protein expression in <i>Spirulina</i>, but not in <i>Chlorella vulgaris</i>.The recombinant <i>Spirulina</i> produced thermostable phycocyanin that retained 74.3% stability at 55ºC compared to 45.3% in the wild type. It also showed slightly higher biomass productivity (7.2% increase) and greater phycocyanin yield (1.0 g/L vs. 0.7 g/L). Importantly, the foreign gene remained stably integrated without antibiotic selection for several months. These findings demonstrate that genetically engineered <i>Spirulina</i> can serve as a cost-effective platform for producing thermostable phycocyanin with improved yield and stability, addressing limitations of current production methods.