Metabolomics and lipid profile analysis of Coccomyxa melkonianii SCCA 048

Abstract

With an unsupervised GC-MS metabolomics approach, polar metabolite changes of the microalgae Coccomyxa melkonianii SCCA 048 grown under standard conditions for seven weeks were studied. C. melkonianii was sampled at the Rio Irvi River, in the mining site of Montevecchio-Ingurtosu (Sardinia, Italy), which is severely contaminated by heavy metals and shows high concentrations of sulfates. The partial-least-square (PLS) analysis of the GC-MS data indicated that growth of C. melkonianii was characterized by an increase of the levels of threonic acid, myo-inositol, malic acid, and fumaric acid. Furthermore, at the sixth week of exponential phase the lipid fingerprint of C. melkonianii was studied by LC-QTOF-MS. C. melkonianii lipid extract characterized through an iterative MS/MS analysis showed the following percent levels: 61.34 ± 0.60% for triacylglycerols (TAG); 11.55 ± 0.09% for diacylglyceryltrimethyl homoserines (DGTS), 11.34 ± 0.10% for sulfoquinovosyldiacylglycerols (SQDG) and, 5.29 ± 0.04% for lysodiacylglyceryltrimethyl homoserines (LDGTS). Noteworthy, we were able to annotate different fatty acid ester of hydroxyl fatty acid, such as FAHFA (18:1_20:3), FAHFA (18:2_20:4), FAHFA (18:0_20:2), and FAHFA (18:1_18:0), with relevant biological activity. These approaches can be useful to study the biochemistry of this extremophile algae in the view of its potential exploitation in the phycoremediation of polluted mining areas.

Keywords: FAHFA; GC–MS; Green algae; LC–MS; Phycoremediation; SQDG.

Fig. 1

a and b habitat of Coccomyxa melkonianii SCCA 048, Rio Irvi SW Sardinia (Italy); c cells of C. melkonianii (Scale bar: 10 μm); d strain cultured for 7 weeks; e time evolution of biomass concentration (g/L DW)

Fig. 2

OPLS correlation plot between experimental (y-axis) and predicted (x-axis) biomass of Coccomyxa melkonianii SCCA 048 (R²Y = 0.99, Q²Y = 0.96)