Paramylon production by Euglena gracilis via mixotrophic cultivation using sewage effluent and waste organic compounds

Abstract Euglena gracilis is a valuable microalga for the production of high-value-added materials such as paramylon. Increasing paramylon productivity and reducing cultivation costs of E. gracilis are critical challenges faced at present. The present study investigated the efficiency of mixotrophic cultivation of E. gracilis using sewage effluent and organic wastes to overcome these bottlenecks. Paramylon production was higher in E. gracilis cultivated in sewage effluent than that using synthetic medium. Supplementing organic wastes, molasses, corn steep liquor, and waste wine to sewage effluent significantly enhanced E. gracilis paramylon production. Acetate and ethanol in the wastes were key components to increase paramylon productivity. Paramylon content in cells and paramylon productivity of E. gracilis in sewage effluent containing waste wine reached 67.7% and 47.8 mg/L/d, respectively. These results indicate that mixotrophic cultivation using sewage effluent and organic wastes is a promising strategy for cost-effective and highly efficient paramylon production by E. gracilis.