Sustainable waste-based fermentation for enhanced β-carotene biosynthesis by Blakeslea trispora and functional evaluation of the extracted pigment.

BACKGROUND

Valorization of agri-food waste as nutrient-rich substrates provides a sustainable strategy for microbial bioprocessing. Blakeslea trispora is a well-known fungal producer of natural β-carotene; however, its performance on low-cost industrial waste streams remains underexplored.

RESULTS

In this study, dairy sludge and soybean meal were evaluated as alternative carbon and nitrogen sources for β-carotene biosynthesis by B. trispora. Response Surface Methodology (RSM) identified an optimized medium containing 12% dairy sludge, 2% soybean meal, and 0.4% yeast extract, yielding 65 g/L biomass and 352 μg/mL β-carotene in laboratory-scale fermentation. The pigment extracted from optimized cultures was confirmed as β-carotene through HPLC, FTIR, and 13C-NMR analyses. Biofunctional assays revealed antimicrobial activity (MIC: 250-500 mg/mL), with greater susceptibility in Gram-positive strains. Moderate antioxidant activity was observed in the DPPH assay (38% inhibition), and cytotoxic evaluation against Caco-2 cells resulted in an IC₅₀ of 400 mg/mL, indicating potential anticancer effects.

CONCLUSION

These findings demonstrate that agri-food wastes can serve as efficient substrates for fungal β-carotene production, supporting cost-effective and sustainable microbial bioprocessing. The functional properties of the extracted β-carotene further highlight its applicability as a bioactive microbial metabolite with antimicrobial, antioxidant, and anticancer potential.