UV–C radiation increases sterol production in the microalga Pavlova lutheri

Plant sterols have become well-known to promote cardiovascular health through the reduction of low density lipoprotein cholesterol in the blood. Plant sterols also have anti-inflammatory, anti-cancer, anti-oxidative and anti-atherogenicity activities. Microalgae have the potential to become a useful alternative source of plant sterols with several species reported to have higher concentrations than current commercial ones. In order to increase phytosterol production and optimise culture conditions, the high sterol producer Pavlova lutheri was treated in different dosages (50–250\ua0mJ\ua0m) of UV–C radiation and several concentrations (1–500\ua0μmol/L) of hydrogen peroxide (HO) and the sterol contents were quantified for two days after the treatments. The contents of malondialdehyde (MDA) superoxide dismutase (SOD) as indications of cell membrane damage by lipid peroxidation and repair of oxidative stress, respectively, were measured. Higher activities of SOD and MDA were observed in the treated biomass when compared to the controls. Total sterols increased in P.\ua0lutheri due to UV–C radiation (at 100\ua0mJ\ua0m) but not in response to HO treatment. Among the nineteen sterol compounds identified in P.\ua0lutheri, poriferasterol, epicampesterol, methylergostenol, fungisterol, dihydrochondrillasterol, and chondrillasterol increased due to UV–C radiation. Therefore, UV–C radiation can be a useful tool to boost industrial phytosterol production from P.\ua0lutheri