Cultivation of the green microalga Coelastrella chongqingensis in lactose-containing media

Currently, various agricultural by-products are being explored as cost-effective alternative media for microalgae cultivation, to enhance biomass productivity and reduce overall production costs. Among these substrates, dairy industry by-products remain particularly challenging to valorize. In this study, the biomass productivity of the axenic Coelastrella chongqingensis MSCL 1802 strain was evaluated under mixotrophic and heterotrophic conditions using cheese whey and whey permeate as alternative cultivation media, and compared to its productivity in a defined synthetic medium. The results demonstrated that the highest biomass productivity was achieved in whey permeate medium under mixotrophic conditions, reaching 0.32 ± 0.01 g L^–1 day^–1 (dry biomass). Furthermore, it was shown that C. chongqingensis can produce β-galactosidase and utilize lactose, i.e., the main sugar present in whey and permeate, under both mixotrophic and heterotrophic conditions.