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

Philipp Doppler,Oliver Spadiut,Heidi Halbwirth,Daniel Remias,Christoph Kornpointner

doi:10.3390/life11020107

Philipp Doppler, Oliver Spadiut + Show 3 more

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https://doi.org/10.3390/life11020107

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Journal: Life	Publication Date: Jan 30, 2021
Citations: 15	License type: CC BY 4.0

Affiliation: TU Wien, University of Applied Sciences Upper Austria

Abstract

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).

Highlights

Microalgal cultures use greenhouse gas carbon dioxide (CO2) as the sole carbon source and the power of light for autotrophic growth
The goal of this work was to characterize the novel strain of Tetraedron minimum to identify the stress factors responsible for its secondary carotenoid accumulation
This study presents the first report of secondary carotenoid production within the green algal family of Hydrodictyaceae

Summary

Introduction

Microalgal cultures use greenhouse gas carbon dioxide (CO2) as the sole carbon source and the power of light for autotrophic growth. A specific class of these compounds are carotenoids Their structure derives from the tetraterpene lycopene, and approx. The microbial accumulation of secondary carotenoids is done to secure cells during harmful environmental conditions, like nutrient starvation, excessive UV, or visible light radiation; extreme temperatures or desiccation; and during the formation of resting cell stages, like cysts [5,12]. It is not always evident if one specific abiotic factor or a combination of several ones is causing secondary carotenoid production. The most used and promising techniques are temperature changes, elevated light radiation, nitrate starvation, and osmotic stress by the addition of salt [14]

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