Thorsmoerkia curvula gen. et spec. nov. (Trebouxiophyceae, Chlorophyta), a semi-terrestrial microalga from Iceland exhibits high levels of unsaturated fatty acids

Abstract

A terrestrial green alga was isolated at Iceland, and the strain (SAG 2627) was described for its morphology and phylogenetic position and tested for biotechnological capabilities. Cells had a distinctly curved, crescent shape with conical poles and a single parietal chloroplast. Phylogenetic analyses of 18S rDNA and rbcL markers placed the strain into the Trebouxiophyceae (Chlorophyta). The alga turned out to belong to an independent lineage without an obvious sister group within the Trebouxiophyceae. Based on morphological and phylogenetic data, the strain was described as a new genus and species, Thorsmoerkia curvula gen. et sp. nov. Biomass was generated in column reactors and subsequently screened for promising metabolites. Growth was optimized by pH-regulated, episodic CO2 supplement during the logarithmic growth-phase, and half of the biomass was thereafter exposed to nitrogen and phosphate depletion. The biomass yield reached up to 53.5 mg L−1 day−1. Fatty acid (FA) production peaked at 24 mg L−1 day−1 and up to 83% of all FAs were unsaturated. At the end of the log phase, approximately 45% of dry mass were lipids, including eicosapentaenoic acid. Carotenoid production reached up to 2.94 mg L−1 day−1 but it was halted during the stress phase. The N-linked glycans of glycoproteins were assessed to reveal chemotaxonomic patterns. The study demonstrated that new microalgae can be found at Iceland, potentially suitable for applied purposes. The advantage of T. curvula is its robustness and that significant amounts of lipids are already accumulated during log phase, making a subsequent stress exposure dispensable.

In Vitro Characterization of Antioxidant, Antibacterial and Antimutagenic Activities of the Green Microalga Ettlia pseudoalveolaris

“…Another green microalga, Chlamydomonas reinhardtii , showed a FAs profile similar to those of E. pseudoalveolaris , being palmitic acids, among SFAs, and ALA, among PUFAs, the most represented FAs [ 43 ]. A study by Nicoletti et al [ 44 ] found that the green microalga Thorsmoerkia curvula also contained significant amounts of ALA, thus confirming the potential of green microalgae as a viable source of ALA with various applications in food, nutraceuticals and animal feed. Although to a lesser extent then PUFAs, monounsaturated fatty acids (MUFAs) were also present in the FAs profile of Ettlia , with palmitoleic (3.35 ± 0.03%) and oleic acid (3.28 ± 0.02%) as the most represented.…”

Coelastrella terrestris for Adonixanthin Production: Physiological Characterization and Evaluation of Secondary Carotenoid Productivity

“…This initial physiological characterization indicates great potential for future industrial use of C. terrestris WP154.1 for both, scalable adonixanthin and polyunsaturated FA production. Due to its climate, Iceland seems to be a promising origin of microbial strains useful for biotechnology, as recently shown for another green microalga [ 31 ].…”

Freshwater ‘microcroissants’ shed light on a novel higher-level clade within Trebouxiophyceae and reveal the genusChlorolobionas a trebouxiophyte

“…Sequences of ACOI 2681 and 3192 were identical for all three molecular markers sequenced and thus we treat these two strains as conspecific. The VMJ + ACOI 2681/3192 cluster was then sister to the Icelandic Thorsmoerkia curvula described by Nicoletti et al (2021) (Fig. 16).…”

“…In some cases, such organisms form deeply branching isolated lineages. A notable example is the recently described semi-aerophytic crescent-shaped Thorsmoerkia curvula, which was not assigned to any of the existing orders or clades and allegedly lacked sequenced close relatives (Nicoletti et al, 2021). Another example of an enigmatic and phylogenetically unresolved lineage is represented by a Navicula-shaped coccoid alga (strain SAG 2477) isolated from soil in Germany, provisionally considered a candidate new species in a new genus in a PhD thesis (Hodač, 2015).…”