Lipidomic analysis can distinguish between two morphologically similar strains of Nannochloropsis oceanica

Development of a screening method for the determination of carotenoids in ham sausage, juice, and cookies by an improved Bligh-Dyer method and LC-MS/MS

A screening method of 23 carotenoids in foods, such as ham sausage, juice, and cookies, was proposed using an improved Bligh-Dyer method that can satisfy the extraction requirements of common carotenoids with different physicochemical properties, including free and esterified carotenoids, by collecting the aqueous and organic phases simultaneously. Purification was then performed by loading the aqueous phase onto a hydrophile-lipophile balance (HLB) column; a methanol-water solution was used for washing, and the organic phases and additional chloroform were used for elution. By optimizing this step, interference from hydrophilic compounds and neutral triglycerides was effectively eliminated, and the matrix suppression effect after purification was greater than -16.3%. Finally, the extract was analyzed by ultrahigh performance liquid chromatography-quadrupole-orbitrap high-resolution mass spectrometry. The results showed that the 23 carotenoids showed a good linear relationship in the range of 0.01-0.2 µg/mL, and the limits of quantification (signal-to-noise ratio ≥10) were from 0.02 to 0.05 mg/kg. The average recoveries were 80.1%-98.7%, with relative standard deviation ≤10%. The proposed method can simultaneously identify and quantify 23 carotenoids in foods with high throughput, sensitivity, and reliability.

A two-prong mutagenesis and adaptive evolution strategy to enhance the temperature tolerance and productivity of Nannochloropsis oculata

Incorporation of microalgae in biorefineries intended to help society reach carbon neutrality is hindered by algal growth inhibition at high temperatures, necessitating the use of costly and carbon-intensive cooling systems. In the present study, a two-prong strategy of random mutagenesis and adaptive laboratory evolution to generate robust thermotolerant strains of Nannochloropsis oculata, was used. The best mutants demonstrated increased productivity at 35 °C, which was 10 °C higher than the optimal temperature of the wild type. In a 2-L photobioreactor at 35 °C, biomass and lipid productivity were 1.43-fold and 2.24-fold higher, respectively, than wild type at 25 °C. Higher pigment and carbohydrate content contributed to the mutants' rapid growth and enhanced photosynthetic efficiency. Metabolomics and lipidomics showed rewiring of the central carbon metabolism and membrane lipid synthesis in thermotolerant strains to ensure cellular homeostasis without compromising productivity. Tagatose and phosphatidylethanolamine upregulation were identified as future genetic targets for further enhancing lipid production.

Combined effect of CO2 concentration and low-cost urea repletion/starvation in Chlorella vulgaris for ameliorating growth metrics, total and non-polar lipid accumulation and fatty acid composition

Different CO₂ concentration such as 0.03, 5, 10 and 15% and low-cost urea repletion/starvation in Chlorella vulgaris on growth, total and non-polar lipid content and fatty acid composition was studied. Chlorella vulgaris grown at 0.03% CO₂ apparently revealed inferior biomass yield 0.55 g/L on 14th day compared to CO₂ supplemented cells. In the case of CO₂ supply, 15% CO₂ has unveiled higher biomass yield at about 1.83 g/L on day 12 whereas biomass yield for 5 and 10% CO₂ supplemented cells was 1.61 and 1.73 g/L, respectively on 12th day of cultivation. The biomass productivity (g) per liter per day was 32 mg in control condition whereas it was 125, 134 and 144 mg/L/d in 5, 10 and 15% CO₂ supplied cells, respectively. Lipid content of the strain grown at control, 5, 10 and 15% CO₂ was 21.2, 22.1, 23.4 and 24.6%, respectively and however, without CO₂ addition in low-cost urea repleted and urea depleted medium grown cells revealed 21.2 and 24.2%, respectively. Interestingly, strain grown at 15% CO₂ supply in urea deplete medium yielded 28.7% lipid and contribution of non-polar lipids in total lipids is 69.7%. Further, the fatty acid composition of the strain grown in 15% CO₂ supply in urea depleted medium showed C16:0, C16:1, C18:1 and C18:3 in the level of 30.12, 9.98, 23.43, and 11.97%, respectively compared to control and urea amended condition.

Applications of lipidomics in marine organisms: Progresses, challenges and future perspectives

Marine ecosystems comprise a high diversity of life forms, such as algae, invertebrates, and vertebrates. These organisms have adapted their physiology according to the conditions of the environments in which...

Ethanol Extraction of Polar Lipids from Nannochloropsis oceanica for Food, Feed, and Biotechnology Applications Evaluated Using Lipidomic Approaches

Nannochloropsis oceanica can accumulate lipids and is a good source of polar lipids, which are emerging as new value-added compounds with high commercial value for the food, nutraceutical, and pharmaceutical industries. Some applications may limit the extraction solvents, such as food applications that require safe food-grade solvents, such as ethanol. However, the effect of using ethanol as an extraction solvent on the quality of the extracted polar lipidome, compared to other more traditional methods, is not yet well established. In this study, the polar lipid profile of N. oceanica extracts was obtained using different solvents, including chloroform/methanol (CM), dichloromethane/methanol (DM), dichloromethane/ethanol (DE), and ethanol (E), and evaluated by modern lipidomic methods using LC-MS/MS. Ultrasonic bath (E + USB)- and ultrasonic probe (E + USP)-assisted methodologies were implemented to increase the lipid extraction yields using ethanol. The polar lipid signature and antioxidant activity of DM, E + USB, and E + USP resemble conventional CM, demonstrating a similar extraction efficiency, while the DE and ethanol extracts were significantly different. Our results showed the impact of different extraction solvents in the polar lipid composition of the final extracts and demonstrated the feasibility of E + USB and E + USP as safe and food-grade sources of polar lipids, with the potential for high-added-value biotechnological applications.

Relative abundance of lipid types among Chlorella sp. and Scenedesmus sp. and ameliorating homogeneous acid catalytic conditions using central composite design (CCD) for maximizing fatty acid methyl ester yield

The present study has tested the biodiesel potential of two hyper lipid producing strains Chlorella sp. and Scenedesmus sp. in terms of biomass yield, quantity and quality of lipid and fatty acid composition. Biomass yield of Chlorella sp. and Scenedesmus sp. was 1.26 and 1.33 g/L, respectively on day 18 and 20. The lipid content and lipid productivity of Chlorella sp. and Scenedesmus sp. was estimated to be 21.3, 26.5% and 12.33, 14.74 mg/L/d, respectively. Notably, relative abundance of lipid types in both the strains revealed >60% neutral lipids followed by glycolipids and phospholipids in minimal level. Central composite design based optimization revealed 69 and 65.4% FAME yield from Chlorella sp. and Scenedesmus sp. at 3% sulphuric acid and 65 °C reaction temperature. Eventually, higher levels of saturated fatty acids (~45%) and monounsaturated fatty acids (~34%) and make Scenedesmus sp. a promising parent material for workable biodiesel production.

An improved method for the separation of carotenoids and carotenoid isomers by liquid chromatography-mass spectrometry

Carotenoids consist of a series of conjugated isoprene units that are characteristically highly conjugated through double bonds, leading to the formation of many isomers that are susceptible to oxidation and other chemical modifications. Extreme hydrophobicity and high complexity make carotenoids difficult to identify and quantify. We implemented the use of a common Syncronis C18 column with strong eluting solvent, here isopropanol, to successfully separate a mixture of 23 carotenoids standards with different structural properties. In addition, the method differentiated between three groups of isomeric carotenoids (lycopene/δ-carotene/γ-carotene/ε-carotene/α-carotene/β-carotene, α-cryptoxanthin/β-cryptoxanthin, and zeaxanthin/lutein) by optimizing the gradient profile and using liquid chrmatography-mass spectrometry. The LOD ranged from 0.05 to 5.51 ng/mL, and the recovery of carotenoids in Mytilus coruscus was from 63.54 to 93.25%, with standard deviations <10%. Twenty-five carotenoids were detected with a total content of 857 ± 55.1 mg/kg, and three isomeric carotenoids were identified: ε-carotene, α-carotene, and β-carotene. Our results show that this methodology is a significant improvement over other alternatives for analyzing carotenoids because of its compatibility with carotenoids of different categories, and most importantly, its ability to resolve isomeric carotenes, which is significant not only for assessing carotenoid species, but also for the tracing of metabolic pathways of carotenoids.

Modulation of Polar Lipid Profiles in Chlorella sp. in Response to Nutrient Limitation

We evaluate the effects of nutrient limitation on cellular composition of polar lipid classes/species in Chlorella sp. using modern polar lipidomic profiling methods (liquid chromatography⁻tandem mass spectrometry; LC-MS/MS). Total polar lipid concentration was highest in nutrient-replete (HN) cultures with a significant reduction in monogalactosyldiacylglycerol (MGDG), phosphatidylglycerol (PG), phosphatidylcholine (PC), and phosphatidylethanolamine (PE) class concentrations for nutrient-deplete (LN) cultures. Moreover, reductions in the abundance of MGDG relative to total polar lipids versus an increase in the relative abundance of digalactosyldiacylglycerol (DGDG) were recorded in LN cultures. In HN cultures, polar lipid species composition remained relatively constant throughout culture with high degrees of unsaturation associated with acyl moieties. Conversely, in LN cultures lipid species composition shifted towards greater saturation of acyl moieties. Multivariate analyses revealed that changes in the abundance of a number of species contributed to the dissimilarity between LN and HN cultures but with dominant effects from certain species, e.g., reduction in MGDG 34:7 (18:3/16:4). Results demonstrate that Chlorella sp. significantly alters its polar lipidome in response to nutrient limitation, and this is discussed in terms of physiological significance and polar lipids production for applied microalgal production systems.

Lipidomic Analysis: From Archaea to Mammals

Lipids are among the most important organic compounds found in all living cells, from primitive archaebacteria to flowering plants or mammalian cells. They form part of cell walls and constitute cell storage material. Their biosynthesis and metabolism play key roles in faraway topics such as biofuel production (third-generation biofuels produced by microorganisms, e.g. algae) and human diseases such as adrenoleukodystrophy, Zellweger syndrome, or Refsum disease. Current lipidomic analysis requires fast and accurate processing of samples and especially their characterization. Because the number of possible lipids and, more specifically, molecular species of lipids is of the order of hundreds to thousands, it is necessary to process huge amounts of data in a short time. There are two basic approaches to lipidomic analysis: shotgun and liquid chromatography-mass spectometry. Both methods have their pros and cons. This review deals with lipidomics not according to the type of ionization or the lipid classes analyzed but according to the types of samples (organisms) under study. Thus, it is divided into lipidomic analysis of archaebacteria, bacteria, yeast, fungi, algae, plants, and animals.

Unambiguous regiochemical assignment of sulfoquinovosyl mono- and diacylglycerols in parsley and spinach leaves by liquid chromatography/electrospray ionization sequential mass spectrometry assisted by regioselective enzymatic hydrolysis

RATIONALE

Sulfoquinovosylmonoglycerides (SQMG) and sulfoquinovosyldiglycerides (SQDG) in the lipid extracts of parsley (Petroselinum crispum) and spinach (Spinacia oleracea) leaves were investigated. The aim of this work was to assess and establish the chemical characterization of fatty acyl chains in sulfolipids (SQMG and SQDG) and their regiochemistry.

METHODS

A key component of this approach is a combination of hydrolysis reactions catalyzed by Lecitase® Ultra, which is a sn₁ -regioselective hydrolase enzyme, and reversed-phase liquid chromatography with electrospray ionization and sequential mass spectrometry (RPLC/ESI-MS) by collision-induced dissociation (CID)-MSⁿ (n = 2, 3).

RESULTS

The occurrence of SQMG bearing 16:0 or 18:3 acyl chains was established for the first time. A regiochemistry-dependent fragmentation pattern of SQMG was attained whereby the sulfoquinovosyl anion ([C₆ H₁₁ O₈ S]^- at m/z 243.0) provides a diagnostic product ion. Regioselective enzymatic treatment also provided a posteriori confirmation of a widely accepted fragmentation rule for SQDG. The sulfoquinovosyl anion was found to play a role also in the fragmentation pattern of SQDG, whose regiochemical assignment could be ultimately confirmed by MS³ experiments.

CONCLUSIONS

The predominant sulfolipid in leaf extracts of raw parsley (Petroselinum crispum) and spinach (Spinacia oleracea) was identified as SQDG 18:3/16:0, along with SQMG 18:3/0:0 and SQMG 16:0/0:0. The present CID-MS-based method can be considered a successful approach to validate the regiochemical characterization of sulfolipids paving the way for their unambiguous characterization.

miR-31 Links Lipid Metabolism and Cell Apoptosis in Bacteria-Challenged Apostichopus japonicus via Targeting CTRP9

The biological functions of microRNAs (miRNAs) have been studied in a number of eukaryotic species. Recent studies on vertebrate animals have demonstrated critical roles of miRNA in immune and metabolic activities. However, studies on the functions of miRNA in invertebrates are very limited. Here, we demonstrated that miR-31 from Apostichopus japonicus disrupts the balance of lipid metabolism, thus resulting in cell apoptosis by targeting complement C1q tumor necrosis factor-related protein 9 (AjCTRP9), a novel adipokine with pleiotropic functions in immunity and metabolism. Lipidomic analysis suggested that the intercellular lipid metabolites were markedly altered, and three ceramide (Cer) species synchronously increased in the AjCTRP9-silenced coelomocytes. Moreover, exogenous Cer exposure significantly induced apoptosis in the coelomocytes in vivo, in agreement with findings from miR-31 mimic- or AjCTRP9 small-interfering RNA-transfected coelomocytes. Furthermore, we found that the imbalance in sphingolipid metabolism triggered by the overproduction of Cers ultimately resulted in the activation of the apoptosis initiator caspase-8 and executioner caspase-3. Our findings provide the first direct evidence that miR-31 negatively modulates the expression of AjCTRP9 and disturbance of Cer channels, thus leading to caspase-3- and caspase-8-dependent apoptosis, during the interactions between pathogens and host.

High-throughput lipidomics enables discovery of the mode of action of huaxian capsule impacting the metabolism of sepsis

Severe sepsis (SS) is a major cause of mortality and morbidity in the intensive care unit and requires rapid diagnosis and treatment.

Lipidomic Approaches towards Deciphering Glycolipids from Microalgae as a Reservoir of Bioactive Lipids

In recent years, noteworthy research has been performed around lipids from microalgae. Among lipids, glycolipids (GLs) are quite abundant in microalgae and are considered an important source of fatty acids (FAs). GLs are rich in 16- and 18-carbon saturated and unsaturated fatty acids and often contain polyunsaturated fatty acids (PUFAs) like n-3 α-linolenic (ALA 18:3), eicosapentaenoic (EPA, 20:5) and docosahexaenoic (DHA, 22:6). GLs comprise three major classes: monogalactosyldiacyl glycerolipids (MGDGs), digalactosyl diacylglycerolipids (DGDGs) and sulfoquinovosyl diacylglycerolipids (SQDGs), whose composition in FA directly depends on the growth conditions. Some of these lipids are high value-added compounds with antitumoral, antimicrobial and anti-inflammatory activities and also with important nutritional significance. To fully explore GLs’ bioactive properties it is necessary to fully characterize their structure and to understand the relation between the structure and their biological properties, which can be addressed using modern mass spectrometry (MS)-based lipidomic approaches. This review will focus on the up-to-date FA composition of GLs identified by MS-based lipidomics and their potential as phytochemicals.