Tetraedron minimum, First Reported Member of Hydrodictyaceae to Accumulate Secondary Carotenoids

• Published in: Life
• Main Authors: Philipp Doppler, Christoph Kornpointner, Heidi Halbwirth, Daniel Remias, Oliver Spadiut
• Format: Text
• Language: English
• Published: Multidisciplinary Digital Publishing Institute 2021
• Subjects: stirred photobioreactor; pigment composition; astaxanthin; adonixanthin; nitrogen starvation; salt stress; palmelloids; antioxidant capacity; fatty acid profile; Iceland
• Online Access: https://doi.org/10.3390/life11020107

We isolated a novel strain of the microalga Tetraedron minimum in Iceland from a terrestrial habitat. During long-term cultivation, a dish culture turned orange, indicating the presence of secondary pigments. Thus, we characterized T. minimum for growth and possible carotenoid production in different inorganic media. In a lab-scale photobioreactor, we confirmed that nitrogen starvation in combination with salt stress triggered a secondary carotenoid accumulation. The development of the pigment composition and the antioxidant capacity of the extracts was analyzed throughout the cultivations. The final secondary carotenoid composition was, on average, 61.1% astaxanthin and 38.9% adonixanthin. Moreover, the cells accumulated approx. 83.1% unsaturated fatty acids. This work presents the first report of the formation of secondary carotenoids within the family Hydrodictyaceae (Sphaeropleales, Chlorophyta).