Engineering the Unicellular Alga Phaeodactylum tricornutum for Enhancing Carotenoid Production

Abstract

Microalgae represent a promising resource for the production of beneficial natural compounds due to their richness in secondary metabolites and easy cultivation. Carotenoids feature among distinctive compounds of many microalgae, including diatoms, which owe their golden color to the xanthophyll fucoxanthin. Carotenoids have antioxidant, anti-obesity and anti-inflammatory properties, and there is a considerable market demand for these compounds. Here, with the aim to increase the carotenoid content in the model diatom Phaeodactylum tricornutum, we exploited genetic transformation to overexpress genes involved in the carotenoid biosynthetic pathway. We produced transgenic lines over-expressing simultaneously one, two or three carotenoid biosynthetic genes, and evaluated changes in pigment content with high-performance liquid chromatography. Two triple transformants over-expressing the genes Violaxanthin de-epoxidase (Vde), Vde-related (Vdr) and Zeaxanthin epoxidase 3 (Zep3) showed an accumulation of carotenoids, with an increase in the fucoxanthin content up to four fold. Vde, Vdr and Zep3 mRNA and protein levels in the triple transformants were coherently increased. The exact role of these enzymes in the diatom carotenoid biosynthetic pathway is not completely elucidated nevertheless our strategy successfully modulated the carotenoid metabolism leading to an accumulation of valuable compounds, leading the way toward improved utilization of microalgae in the field of antioxidants.

Role of Fucoxanthin towards Cadmium-induced renal impairment with the antioxidant and anti-lipid peroxide activities

“…In recent years, fucoxanthin has been widely investigated due to its powerful antioxidant and free radical scavenging ability [23][24][25]. The apoptosis induced by oxidative stress is one of the primary mechanisms that are in place in regard to the toxic effects of the heavy metal cadmium [26,27].…”

Anti-Inflammatory and Anticancer Effects of Microalgal Carotenoids

“…and Microcystis aeruginosa [42], as well as the microalgae Nannochloropsis oculata (Ochrophyta, Eustigmatophyceae) [43], Chloroidium saccharophilum (formerly Chlorella saccharophila) [44], and Dunaliella sp. [45], and red algae such as Porphyridium purpureum (formerly Porphyridium cruentum) (Rhodophyta) [35], Phaeodactylum tricornutum (Bacillariophyta) [46], or Heterosigma akashiwo (Ochrophyta, Raphidophyceae) [47]. 1D) is a xantophyll mainly found in microalgae, marine invertebrates, some fishes like salmon and trout, and even in the feathers of some birds, contributing to their red-orange pigmentation [48].…”

“…This carotenoid is present in a variety of macroalgae, but also in a multitude of species of microalgae such as Isochrysis sp. (Haptophyta), Odontella aurita [54,55], Nitzschia laevis (formerly Nitzschia amabilis) [56], and Chaetoceros neogracili (formerly Chaetoceros gracilis) (Bacillariophyta), the coccolithophore Pleurochrysis carterae (Haptophyta, Coccolithophyceae) [57], Phaeodactylum tricornutum (Bacillariophyta) [46], and the microalga strain Pavlova sp. OPMS 30543 (Haprophyta) [58].…”

Unlocking the Health Potential of Microalgae as Sustainable Sources of Bioactive Compounds

“…Diatoms show different metabolic features compared to plants [ 26 ] and use unique pigments, that are not present in other species, for light harvesting and photoprotection [ 27 ]. The biosynthetic carotenoid pathway is still not completely understood, and the reactions and enzymes from violaxanthin to diadinoxanthin are still hypothetical [ 28 ]. Lohr and Wilhelm 1999 and Dambek et al 2012 [ 29 , 30 ] proposed the hypothesized pathway of carotenoid biosynthesis in Phaeodactylum tricornutum.…”

“…Lohr and Wilhelm 1999 and Dambek et al 2012 [ 29 , 30 ] proposed the hypothesized pathway of carotenoid biosynthesis in Phaeodactylum tricornutum. However, there is a great interest in increasing carotenoid production and a recent study used genetic transformation of this diatom to increase its carotenoid content [ 28 ].…”