Growth performance and lipid profile of psychrophilic strains Chlorella sp., Haematococcus lacustris, Scenedesmus sp. and Chlamydomonas reinhardtii under different synthetic media and light irradiation

This study investigates how growth conditions-specifically synthetic media (Z8 and BBM) and light wavelength (white, red, and blue)-affect lipid accumulation in psychrophilic microalgae species: Chlorella sp., Haematococcus lacustris, Scenedesmus sp., and Chlamydomonas reinhardtii. Red and blue light negatively impacted biomass production in Chlorella sp. and Scenedesmus sp. when grown in BBM. H. lacustris growth was strongly dependent on the medium used, while C. reinhardtii was adversely affected by red light in BBM. Scenedesmus sp. showed higher lipid accumulation under white and red light (20.80 % and 35.57 %, respectively), and the media influenced the fatty acid composition, particularly linoleic, linolenic, and stearic acids. In contrast, C. reinhardtii lipid storage was unaffected by medium or light, although unique fatty acids such as roughanic acid and 4,7,10,13-hexadecatetraenoate were identified. Chlorella sp. lipid content and composition were influenced by red and blue light in BBM but remained unchanged in Z8. In H. lacustris, red and blue light increased lipid accumulation by 15 %. While BBM maintained stable lipid composition, blue light in Z8 altered levels of linolenic acid and 4,7,10,13-hexadecatetraenoic acid. These findings contribute to fill a research gap regarding the lipid productivity of psychrophilic microalgae and highlight their potential applications in a sustainable and cross-sectoral bioeconomy.