Production of Macromolecules by Chlorella fusca Using Brewery Wastewater as a Nutritional Source

Microalgae are photosynthetic microorganisms capable of metabolizing components present in effluents into biomass. Treating effluents through microalgae cultivation is a sustainable alternative for reducing the production costs of biomass rich in high-value compounds that can be applied across various industries, from food to pharmaceuticals. This study aimed to investigate how brewery wastewater modifies the content of carbohydrates, lipids, and proteins in the microalga Chlorella fusca LEB 111. Cultures were conducted in duplicate in batch mode, using 2 L photobioreactors at 30°C. Two concentrations of brewery wastewater were tested as a substitute for the standard growth medium (BG-11): EA50 (50% distilled water and 50% wastewater) and E100 (100% wastewater), with a control assay using the BG-11 medium. Each tested condition was maintained until the fourth day of the stationary growth phase. The final biomass was lyophilized and analyzed for proteins, carbohydrates, and lipids. The composition of the biomass revealed that the EA50 and E100 assays (44.57% and 43.22% w.w-1, respectively) did not show a decrease in protein content when compared to the assay without the addition of effluent (47.67% w.w-1) (p>0.05). However, the E100 assay showed significantly higher values (p<0.05) for carbohydrates (30.49% w.w-1) and lipids (34.29% w.w-1) compared to the control condition (24.24% and 25.05% w.w-1, respectively). Thus, a significant increase in the analyzed biocompounds was observed in the E100 assay, making this condition the most favorable among those tested. Compared to the control, the higher concentrations of carbohydrates and lipids in the E100 assay suggest that the lack of nitrogen and phosphorus in brewery wastewater redirected metabolism towards producing reserve compounds. However, there was no loss of nutritional value in the biomass, indicating that using this effluent as a cultivation substrate holds promise for sustainable biomass production with potential industrial applications.