Synergistic heterotrophic-photomixotrophic cultivation enhances fucoxanthin production in Poterioochromonas malhamensis (golden microalga)

Fucoxanthin is a highly commercially valuable carotenoid derived from algae. The golden microalga Poterioochromonas malhamensis shows promise as a source of fucoxanthin, but the commercial viability is hindered by its low fucoxanthin content and productivity. This study introduces a novel heterotrophic-photomixotrophic approach in which P. malhamensis was initially cultivated heterotrophically and then shifted to photomixotrophic culture conditions. This process achieved a remarkable fucoxanthin content of 1.58 % and a productivity rate of 12.4 mg L −1 d −1 , representing a 10-fold increase in content and a 2-fold increase in productivity compared to previous studies. Transcriptome analysis revealed preliminary mechanisms driving these improvements, including enhanced precursor supply, regulation of transcription factors, and catabolism of β-1, 3-glucans. Furthermore, techno-economic analysis indicates that this novel approach presents a competitive advantage over existing fucoxanthin production systems based on diatom Phaeodactylum tricornutum . This work provides an innovative and commercially promising pathway for the scalable production of fucoxanthin.