Liberti, Davide (2023) Microalgae as biorefinery: development of processes for the green extraction of high added value antioxidants. [Tesi di dottorato]

Anteprima

Testo Davide_Liberti_XXXV_cycle.pdf Download (47MB) | Anteprima

Abstract

Nowadays, the strategy of biorefinery perfectly fits with the circular bioeconomy concept and microalgae can be considered excellent candidates for their use in biorefinery approaches. Indeed, microalgae are a reliable source of natural compounds with different biological activities, they perform carbon capture and can grow in lands which do not compete with food production. The aim of the present PhD project was the complete exploitation of Porphyridium cruentum culture to obtain different high value products in a cascade approach. Sulphated exopolysaccharides (s-EPSs) were isolated from the culture medium and a chemical characterization was obtained. Different procedures to harvest the biomass were compared, and biomass storage was analyzed in the context of phycoerythrin (PE) yield. Phycoerythrin isolation was defined upon evaluation of different techniques. The obtained purity grade of the protein was so high that its X-ray structure was determined at 1.60 Å resolution and the protein sequence was determined. Then, carotenoids and lipids were extracted from the residual biomass in two sequential steps and a complete chemical characterization was achieved. In-vitro and cell-based assays were performed to assess the biological activities of these compounds. The s-EPSs, thanks to the presence of sulphate groups, showed biocompatibility on immortalized eukaryotic cell lines and a high antioxidant activity on cell-based systems. PE showed powerful antioxidant activity both in vitro and on cell-based systems, but its purification is mandatory for its safe use. Finally, both molecules showed anti-inflammatory activity comparable to that of Ibuprofen and helped tissue regeneration. The obtained results could boost the industrial utilization of P. cruentum offsetting the high downstream processes cost. Moreover, the simultaneous microalgae culture valorization and carbon capture can contribute to the sustainable expansion of microalgae market.

Downloads

Actions (login required)

Modifica documento