Production of carotenoids from Phormidium sp. microalgae

The recovery of bioactive compounds as carotenoids from agroindustrial wastewater cultivated microalgae by environmentally friendly techniques such as Ultrasound-Assisted Extraction (UAE) can provides the double opportunity to obtain high-added value biomolecules and to reduce the possible environmental damage. In this study, the carotenoid profile and antioxidant capacity of ultrasound-assisted extracts from microalgae Phormidium sp. cultivated in agroindustrial wastewater were investigated. The experiments were carried out in a bubble column bioreactor (initial inoculum of 0.1 g.L⁻¹, 26°C, continuous aeration of 1 VVM, C/N ratio 30, absence of light and residence time of 7 days). The carotenoids were extracted in a ultrasonic processor for 20 min at 20 kHZ. The amplitude of the sonicator probe was 40%. The carotenoids were determined by high performance liquid chromatography coupled to photodiode array detector (HPLC-PDA) on a C₃₀ column. Additionally, the in vitro scavenging capacity of the carotenoid extract against ROO^· was evaluated. A total of twenty carotenoids were separated in the extracts and among these all-trans-b-carotene was the major carotenoid found, followed by all-trans-lutein and all-trans-zeaxanthin. The carotenoid extract was shown to be a potent scavenger of peroxyl radical, being almost 22 times more potent than a-tocopherol. In summary, the heterotrophic cultivated microalgae is shown as an alternative, renewable and low cost source for obtaining carotenoids with high antioxidant potential to be exploited for a wide range of applications.