Light spectra influence biomass and phenolics while sustaining high fucoxanthin in the tropical indigenous diatom Thalassiosira weissflogii
Abstract
Microalgae are promising sustainable sources of bioactive compounds for food and pharmaceutical applications. The tropical indigenous diatom Thalassiosira weissflogii TRG10-P105 (TW P105), distinguished by its high fucoxanthin (Fx) and phenolic content, was investigated under various light spectra to evaluate biomass and metabolite productivity for industrial cultivation. Cultures were grown under white, red, blue, combined red–blue, and white supplemented with UV-A light, and assessed for growth, pigment composition, Fx, and total phenolic content (TPC). Broad-spectrum white light supported the highest growth (30.17 ± 2.06% d⁻¹), biomass productivity, chlorophylls, carotenoids, and TPC (8.63 ± 0.07 mg GAE g⁻¹ DW). Meanwhile, Fx levels remained consistently high across spectra (17.27–18.49 mg g⁻¹ DW), indicating that TW P105 maintains near-maximal Fx accumulation under low-light conditions, with only minor modulation by light quality. UV-A exposure, though initially inhibitory, activated protective responses that reshaped pigment and phenolic metabolism. These findings show that spectral quality can be applied to fine-tune phenolic and antioxidant production, while white light maximizes biomass and carotenoid yields. The exceptional stability and consistently high Fx content of TW P105, even under various light condition and exceeding most previously reported values by 1.9–13.2 fold, highlight its potential as a robust candidate for sustainable fucoxanthin production. This study provides a technical foundation for spectral control in large-scale algal production and supports the industrial potential of TW P105 as a scalable, cost-effective source of fucoxanthin-rich biomass for nutraceutical, functional food, and pharmaceutical applications.