Heterotrophic growth and lipid accumulation of Chlorella protothecoides in whey permeate, a dairy by-product stream, for biofuel production

This study proposes a novel alternative for the utilization of whey permeate, a by-product stream from the dairy industry, as the feedstock for the biomass and lipid production of the microalgae Chlorella protothecoides. Glucose and galactose from the pre-hydrolyzed whey permeate were used as main carbon sources in a base mineral media for establishing batch and fed batch cultures. Batch cultures reached a biomass production of 9.1 ± 0.2 g/L with a total lipid accumulation of 42.0 ± 6.6% (dry weight basis), while in the fed batch cultures 17.2 ± 1.3 g/L of biomass with 20.5 ± 0.3% lipid accumulation (dry weight basis) were obtained. A third strategy for the direct utilization of whey permeate was investigated by simultaneous saccharification and fermentation (SSF), wherein, 7.3 ± 1.3 g/L of biomass with 49.9 ± 3.3% lipid accumulation (dry weight basis) was obtained in batch mode using immobilized enzyme.