Mechanism of lactose assimilation in microalgae for the bioremediation of dairy processing side-streams and co-production of valuable food products

Abstract This study investigated the mechanism of lactose assimilation in Nannochloropsis oceanica for dairy-wastewater bioremediation and co-production valuable feed/food ingredients a circular dairy system (β-galactosidase omega-3 polyunsaturated fatty acids). Mixotrophic cultivation was found to be mandatory N. , with biomass production mixotrophic cultures reaching fourfold increase over that under heterotrophic conditions. Under conditions, microalgae were able produce β-galactosidase enzyme hydrolyse lactose, maximum extracellular secretion recorded on day 8 growth cycle at 41.47 ± 0.33 U g −1 . No concentration glucose or galactose observed medium, confirming ability indiscriminately absorb resultant monosaccharides derived from breakdown. Population analysis revealed cells maintain dominance culture, bacteria accounting < 12% biomass. On other hand, native took culture (occupying 95% total biomass). The bacteria, however, also unable effectively assimilate resulting limited negligible β-galactosidase. Results indicate can applied onsite wastewater treatment strict is commercially disadvantageous as it rules out possibility deploying fermentation low-cost bioreactors smaller areal footprint.