Value-added co-products from biomass of the diatoms Staurosirella pinnata and Phaeodactylum tricornutum

Microalgae bioprospecting indicates diatoms as a promising resource for biotechnology, with multiple extractions, and intermediate valorization protocols able to open new paths in biomedical, food and feed, and bioenergy fields. The biomass of two diatoms, Phaeodactylum tricornutum and Staurosirella pinnata, was sequentially extracted to obtain crude extracts, cellular lipids, and biomethane by means of compatible protocols. Hydrophilic fractions of crude extracts were characterized for their bioactivity on human melanoma (CHL-1) and keratinocytes (HaCaT) cell lines, with S. pinnata extract showing efficient anti-proliferative and cell death inducing activities only on CHL-1. Total lipids were extracted from residual biomass, and their chromatographic profiles evidenced percental amounts of eicosapentaenoic, hexadecenoic, and octadecanoic acid, exploitable in food and feed sectors. Finally, exhausted biomass was used for biomethane production, with P. tricornutum showing the highest rate. Cascade extraction from diatom biomass prospected potential to optimize the production of algal chemicals and their further biotechnological application.