Table 4 Examples of conventional chromatographic/spectrometric methods for lipid quantification and profiling of oleaginous microorganisms
Method | Microorganisms | Sample preparation | Compound detection and quantification | Correlation with method | Outcome | Reference |
|---|---|---|---|---|---|---|
FABMS | Chlorella vulgaris, Scenedesmus obliquus | Algal cells, intact | Semi-quantitative analysis of fatty acids, TAGs | – | More flexible and versatile than GC | [85] |
GC-MS | Chlorella kessleri, C. vulgaris, Scenedesmus acuminatus, Spirulina platensis | Solvent extraction of dried cells Transesterification | Saturated and unsaturated straight-chain methyl fatty acids, iso- and anteisoacids branched on other carbon atoms and cyclopropane fatty acids | – | Fatty acid profiling | [88] |
GC-MS | Chlamidomonas nivalis | In situ transesterification | Fatty acid profiling | – | Fatty acid biomarkers correspond to response and adaptation to NaCl stress | [89] |
Pyrolysis GC-MS | Chlamydomonas reinhardtii, B. braunii | Lyophilized algae culture, Immersion into isopropanol | C8 to C40 pyrolysis products | – | Automated manner without sample preparation 30 min run times, sequences up to 48 samples | [90] |
Pyrolysis GC-MS | 26 microalgae and cyanobacteria | Whole cells, freeze-dried | Biochemical composition (lipids, protein, carbohydrate) | Gravimetric | Fast analysis (1 h), minimal sample amount (< 0.1 mg), no sample preparation | [91] |
GC-MS sub-microscale assay | Mallomonas splendens, Nannochloropsis oculata, Chrysochromulina sp., Emiliania huxleyi, Rhodomonas sp., Prorocentrum micans | In situ transesterification | Saturated and unsaturated methyl fatty acids | BODIPY, flow cytometry | Minimal size requirement (250 μg dry biomass per sample), fast, less solvent than AOAC and AOCS | [44] |
MALDI-TOF-MS, ESI-LTQ-Orbitrap MS | 7 algal species | Solvent extraction | TAG profile | – | Direct analysis | [92] |
DTD-GC x GC-TOF-MS | Limnothrix sp., Scenedesmus acutus, Chironomous plumosus, Daphnia galatea | Thermally assisted hydrolysis and methylation | FAMEs | – | Analysis of lipid markers for food-web, ecological and clinical studies | [93] |
MS/MS-CID employing paper spray ionization | Kyo-Chlorella, Nannochloropsis | Whole cells, lyophilized | Polar lipid profiling (glycolipids, phospholipids), double bond position determination | – | Structural determination of polar lipids, minimal sample preparation, low sample amount (0.5 μg) | [94] |
UPLC-MS, ESI-MS/MS, ESI-MS | 4 Dunaliella species | Solvent extraction | TAGs, free fatty acids | – | Low sample concentration, small-scale experiments | [95] |
HPLC-ELSD | C. reinhardtii, Chlorella strains | Solvent extraction from dried pellets | TAGs, carotenoids, DAGs, free fatty acids, phospholipids, galactolipids | Comparison with TLC/GC, gravimetric, GC/MS | 15 min run, detectable TAG levels > 0.5 μg/g dry weight | [96] |
HPLC-ELSD, preparative | Scripsiella sp. | Solvent extraction by modified Bligh & Dyer, transesterification and FAME were purified with TLC | Polyunsaturated fatty acids | – | Polyunsaturated fatty acids purification, enrichment and purification of uncommon VLC polyunsaturated fatty acids | [97] |
HPLC-ELSD/MS | Chlorella | Solvent extraction, Folch method | TAGs, hydrocarbons | – | No derivatization needed for determining lipid molecules in one peak | [98] |