Lutein Production by Microalgae Using Corn Starch Wastewater Pretreated with Rapid Enzymatic Hydrolysis

Corn starch wastewater is nontoxic and rich in nutrients, thus, could be regarded as a potential feedstock for lutein biosynthesis by microalgae. For this bioconversion process, the pretreatment process and utilization improvement of nutrients in wastewater are the two key issues. In this study, one-stage enzymatic hydrolysis utilizing α-amylase and glucoamylase simultaneously was established to efficiently enhance the reducing sugar content released by hydrolysis of starch macromolecules with a maximum concentration of 7.26 g/L harvested in 50 minutes. Furthermore, a cyclic feeding cultivation strategy was developed where the spent starch wastewater after microalgae harvesting was supplemented with nitrogen and phosphorus to improve lutein accumulation and COD removal up to 25.9 mg/L and 50.7% after three cultivation cycles with further implementation in actual wastewater. This work provided a new perspective in developing the potential of cultivating microalgae with corn starch wastewater to produce high-value lutein