The commercial cultivation of microalgae began in the 1960s and Chlorella was one of the first target organisms. The species has long been considered a potential source of renewable energy, an alternative for phytoremediation, and more recently, as a growth and immune stimulant. However, Chlorella vulgaris, which is one of the most studied microalga, has never been comprehensively profiled chemically. In the present study, comprehensive profiling of the Chlorella vulgaris metabolome grown under normal culture conditions was carried out, employing tandem LC-MS/MS to profile the ethanolic extract and GC-MS for fatty acid analysis. The fatty acid profile of C. vulgaris was shown to be rich in omega-6, -7, -9, and -13 fatty acids, with omega-6 being the highest, representing more than sixty percent (>60%) of the total fatty acids. This is a clear indication that this species of Chlorella could serve as a good source of nutrition when incorporated in diets. The profile also showed that the main fatty acid composition was that of C₁₆-C₁₈ (>92%), suggesting that it might be a potential candidate for biodiesel production. LC-MS/MS analysis revealed carotenoid constituents comprising violaxanthin, neoxanthin, lutein, β-carotene, vulgaxanthin I, astaxanthin, and antheraxanthin, along with other pigments such as the chlorophylls. In addition to these, amino acids, vitamins, and simple sugars were also profiled, and through mass spectrometry-based molecular networking, 48 phospholipids were putatively identified.

This study was designed to profile the metabolites of Isochrysis galbana, an indigenous and less explored microalgae species. ¹H Nuclear Magnetic Resonance (NMR) spectroscopy and Liquid Chromatography-Mass Spectrometry (LCMS) were used to establish the metabolite profiles of five different extracts of this microalga, which are hexane (Hex), ethyl acetate (EtOAc), absolute ethanol (EtOH), EtOH:water 1:1 (AqE), and 100% water (Aq). Partial least square discriminant analysis (PLS–DA) of the generated profiles revealed that EtOAc and Aq extracts contain a diverse range of metabolites as compared to the other extracts with a total of twenty-one metabolites, comprising carotenoids, polyunsaturated fatty acids, and amino acids, that were putatively identified from the NMR spectra. Meanwhile, thirty-two metabolites were successfully annotated from the LCMS/MS data, ten of which (palmitic acid, oleic acid, α-linolenic acid, arachidic acid, cholesterol, DHA, DPA, fucoxanthin, astaxanthin, and pheophytin) were similar to those present in the NMR profile. Another eleven glycerophospholipids were discovered using MS/MS-based molecular network (MN) platform. The results of this study, besides providing a better understanding of I.galbana’s chemical make-up, will be of importance in exploring this species potential as a feed ingredient in the aquaculture industry.

The commercial cultivation of microalgae began in the 1960s and Chlorella was one of the first target organisms. The species has long been considered a potential source of renewable energy, an alternative for phytoremediation, and more recently, as a growth and immune stimulant. However, Chlorella vulgaris, which is one of the most studied microalga, has never been comprehensively profiled chemically. In the present study, comprehensive profiling of the Chlorella vulgaris metabolome grown under normal culture conditions was carried out, employing tandem LC-MS/MS to profile the ethanolic extract and GC-MS for fatty acid analysis. The fatty acid profile of C. vulgaris was shown to be rich in omega-6, -7, -9, and -13 fatty acids, with omega-6 being the highest, representing more than sixty percent (>60%) of the total fatty acids. This is a clear indication that this species of Chlorella could serve as a good source of nutrition when incorporated in diets. The profile also showed that the main fatty acid composition was that of C16-C18 (>92%), suggesting that it might be a potential candidate for biodiesel production. LC-MS/MS analysis revealed carotenoid constituents comprising violaxanthin, neoxanthin, lutein, β-carotene, vulgaxanthin I, astaxanthin, and antheraxanthin, along with other pigments such as the chlorophylls. In addition to these, amino acids, vitamins, and simple sugars were also profiled, and through mass spectrometry-based molecular networking, 48 phospholipids were putatively identified.

Significant measures at improving aquaculture health have to be taken since disease outbreaks commonly occur in the fast-growing aquaculture industry. This study aimed to determine the immunomodulatory properties of an indigenous Malaysian microalgae species, Isochrysis galbana (IG), on red hybrid tilapia (Oreochromis spp.). Then, the potential biomarkers for immunomodulatory properties were identified through metabolic changes in the spleen using the proton nuclear magnetic resonance (¹H NMR) metabolomics approach. IG was cultivated in an indoor annular photobioreactor before being harvested and freeze-dried into dried biomass. The dried IG biomass was incorporated into four experimental diets in concentrations of 0% (diet A), 0.6% (diet B), 1.3% (diet C), 2.5% (diet D), and 5.0% (diet E) basal feed per kg. After 14 days of feeding, diet D has consistently improved the immune responses of innate immunity such as phagocytosis ( ), respiratory burst ( ), and lymphoproliferation ( ) activities which might have helped in maintaining the overall health status of red hybrid tilapia. The orthogonal partial least squares (OPLS) model between diets D and A indicated three important metabolites, namely, isoleucine, glutamate, and tyrosine, have significantly been upregulated when compared to the control. Meanwhile, IG supplementation also resulted in lower concentrations of various metabolites in the spleen including α/β-glucose, choline, hypoxanthine, adenosine, and inosine. Hence, the application of metabolomics tools has proved the potential of IG-incorporated fish diet by strongly influencing the metabolic condition in red hybrid tilapia spleen cells and further boosting the immune response and health status in improving aquaculture health.

Introduction: In the present study, profiling of the cultured Chlorella vulgaris metabolome was carried out via1H NMR metabolite profiling of 6 different solvent extracts. The results indicated that the six solvent extracts have metabolite profiles that are clearly different from each other. Methods: Multivariate data analysis (MVA) reveals that ethyl acetate and ethanol extracts were well separated from the aqueous extract by PC1 while being well separated from each other by PC2. The same observations were seen with chloroform and 50% ethanol extracts. In contrast, the chemical shift signals for hexane extract clusters in-between that of chloroform and 50% ethanol, indicated that they have similar chemical profiles. Using partial least square discriminative analysis (PLS-DA), compounds responsible for the group separation were identified from the loading plot. Detailed examination of the loading plot shows that ethanol and ethyl acetate extracts contain significantly higher amounts of carotenoids, amino acids, vitamins and fatty acids. A total of 35 compounds were detected from the 6 different solvents upon which the ethanolic and ethyl acetate extracts were identified to contain more metabolites and in a wider range than the other organic solvent extracts. Results: Hence, these two extracts would be more appropriate in metabolite extraction for analysis and for medicinal purposes. Therefore, NMR spectroscopy, in compliment with the right choice of solvent for extraction, could be utilized by relevant industries to evaluate and obtain maximum important metabolites in a shorter time. Conclusion: In addition to possession of high diverse metabolites, the microalgae C. vulgaris could serve as an important functional food ingredient in the aquaculture industry and may possibly be considered as a source of biofuel.