Bioconversion of food wastewater into Penicillium roqueforti AF26 biomass proteins suitable for aquafeed.

The increasing need for aquaculture activities requires access to enough high-quality feed. Many commercial aquafeeds contain fishmeal as a main component, but this is a costly protein source. Therefore, shifting from traditional ingredients to alternative protein sources such as filamentous fungi biomass may alleviate concerns related to the cost of aquafeed. The aim of this study is to evaluate the biomass protein production by a filamentous fungus belonging to the genus Penicillium through the fermentation of food wastewater, specifically citrus wastewater and yogurt whey. In addition, the effect of supplementing wastewater with a nitrogen source (ammonium sulfate, (NH₄)₂SO₄, or urea, CO(NH₂)₂) on protein production performance was assessed. The fungus strain, named Penicillium roqueforti AF26, showed growth dependent on the increase in wastewater concentration, exhibiting greater biomass production on undiluted substrates: 3.83 ± 0.08 g/L on citrus wastewater and 22.7 ± 2.0 g/L on yogurt whey. Protein productivity enhanced significantly when wastewater was supplemented with (NH₄)₂SO₄, reaching values of 16.9 mg/L × h in citrus wastewater and 80.7 mg/L × h in yogurt whey. Proximate analysis of biomass with the highest protein productivity (biomass produced on undiluted yogurt whey supplemented with 1 g/L (NH₄)₂SO₄) revealed a total protein content (25.5%), fat (2.7%), crude fiber (3.6%), ash (15.0%), moisture (9.9%), and carbohydrate (46.9%) within reference ranges reported for commercial aquafeed. This study recorded the feasibility of a P. roqueforti strain to transform food wastewater into a sustainable and alternative protein source to be introduced in the aquaculture industry.