Natural β-Carotene Production by Blakeslea trispora Cultivated in Spanish-Style Green Olive Processing Wastewaters

In the current research, the potential of Spanish-style green olive processing wastewaters (lye and washing waters) exploitation toward natural beta-carotene production by Blakeslea trispora was tested for the first time. Mating culture generated by the joint cultivation of the heterothallic fungal strains ATCC 14271 and 14272 in the non-sterile lye and washing waters was able to grow, achieving the phytotoxic hydroxytyrosol degradation by 57.3% and 66.8%, respectively. However, the low sugar and nitrogen content of the streams did not favor carotenogenesis. Alternatively, in the nutrient-enriched effluents, a notable quantity of beta-carotene was produced, accounted for 61.2 mg/L (lye) and 64.1 mg/L (washing waters) (82-88% of total carotenoid content). Above all, enriched streams had a noteworthy stimulating effect on the beta-carotene synthesis, because both the maximum beta-carotene yield per volume of enriched effluents and specific beta-carotene production rate were higher when compared with the respective values obtained from trials with synthetic reference medium without added effluents. Hydroxytyrosol and tyrosol showed high stability during the non-sterile process for beta-carotene production by B. trispora grown in the enriched effluents. This finding strengthens the potential toward the generation of multiple high-value products, which could lower the natural beta-carotene production costs.

Automated summary

The study tested the potential of utilizing Spanish-style green olive processing wastewaters for natural beta-carotene production by Blakeslea trispora, demonstrating higher beta-carotene yields in nutrient-enriched effluents. However, the low sugar and nitrogen content in the wastewaters were found to be unfavorable for carotenogenesis.