Abstract
The industrial microalga Tetraselmis sp. CTP4 is a promising candidate for aquaculture feed, novel food, cosmeceutical and nutraceutical due to its balanced biochemical profile. To further upgrade its biomass value, carotenogenesis was investigated by testing four environmental factors, namely temperature, light intensity, salinity and nutrient availability over different growth stages. The most important factor for carotenoid induction in this species is a sufficient supply of nitrates leading to an exponential growth of the cells. Furthermore, high temperatures of over 30 °C compared to lower temperatures (10 and 20 °C) induced the accumulation of carotenoids in this species. Remarkably, the two different branches of carotenoid synthesis were regulated depending on different light intensities. Contents of β-carotene were 3-fold higher under low light intensities (33 μmol m−2 s−1) while lutein contents increased 1.5-fold under higher light intensities (170 and 280 μmol m−2 s−1). Nevertheless, highest contents of carotenoids (8.48 ± 0.47 mg g−1 DW) were found upon a thermal upshift from 20 °C to 35 °C after only two days at a light intensity of 170 μmol m−2 s−1. Under these conditions, high contents of both lutein and β-carotene were reached accounting for 3.17 ± 0.18 and 3.21 ± 0.18 mg g−1 DW, respectively. This study indicates that Tetraselmis sp. CTP4 could be a sustainable source of lutein and β-carotene at locations where a robust, euryhaline, thermotolerant microalgal strain is required.
Highlights
In recent years, consumer interest in healthy food and natural products has been growing due to a rising awareness that a healthy nutrition can increase life expectancy
The aim of this study is to provide knowledge of how carotenoid biosynthesis is regulated in Tetraselmis microalgae and where carotenoids accumulate in this chlorophyte
Microalgal cells contained detectable amounts of neoxanthin, zeaxanthin and αcarotene. These results suggest that this strain has two active branches of the carotenoid biosynthetic pathway (Fig. 1B): one giving rise to α-carotene and lutein, and a second one leading to the biosynthesis of β-carotene and other high-value xanthophylls [22]
Summary
Consumer interest in healthy food and natural products has been growing due to a rising awareness that a healthy nutrition can increase life expectancy. Evidence has been put forward that ingredients used as nutraceuticals and cosmeceuticals may confer additional health and medical benefits such as a decreased risk for chronic disease or cancer [1]. This has led to research efforts for the development of food supplements and cosmetics from natural sources. Microalgae can be cultivated in bioreactors or ponds placed on non-arable land, for example, deserts or shorelines, not competing with plant production. They display higher productivities than land crops [3]
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