Phycoremediation of cheese whey permeate using directed commensalism between Scenedesmus obliquus and Chlorella protothecoides

The objective of this work is to explore a new phycoremediation strategy to convert a dairy by-product into microalgal biomass. A culture strategy involving two different green microalgae species was used to remove lactose from cheese whey permeate. First a co-cultivation experiment involving Scenedesmus obliquus and Chlorella protothecoides showed better utilization of the different sugars (lactose, glucose and galactose) than homogeneous S. obliquus cultures. In a second experiment, sequential cultivation of the two microalgal species allowed to convert 62% of the total lactose into 6.8 ± 0.2 g L− 1 and 6.2 ± 0.4 g L− 1S. obliquus and C. protothecoides cultures respectively, for a “lactose-to-biomass” yield (Yx/s) of 0.45. This type of beneficial interaction between two different microbial species represents a simple and sustainable way to improve and diversify the possibilities in the field of industrial microbiology.