Esterified carotenoids as new food components in cyanobacteria

Alternative green solvents associated with ultrasound-assisted extraction: A green chemistry approach for the extraction of carotenoids and chlorophylls from microalgae

This study proposes a method for the ultrasonic extraction of carotenoids and chlorophyll from Scenedesmus obliquus and Arthrospira platensis microalgae with green solvents. Ethanol and ethanolic solutions of ionic liquids were tested with a variety of extraction parameters, including number of extractions, time of extraction, and solid-liquid ratio R(S/L), to determine the optimal conditions. After selecting the most effective green solvent (ethanol), the process conditions were established: R(S/L) of 1:10, three extraction cycles at 3 min each), giving an extraction yield of 2602.36 and 764.21 μgcarotenoids.gdried biomass-1; and 22.01 and 5.81 mgchlorophyll.gdried biomass-1 in S. obliquus and A. platensis, respectively. The carotenoid and chlorophyll extracts obtained using ethanol were shown to be potent scavengers of peroxyl radical, being 5.94 to 26.08 times more potent α-tocopherol. These findings pave the way for a green strategy for valorizing microalgal biocompounds through efficient and environmentally friendly technological processes.

Structure and biosynthesis of carotenoids produced by a novel Planococcus sp. isolated from South Africa

BACKGROUND

The genus Planococcus is comprised of halophilic bacteria generally reported for the production of carotenoid pigments and biosurfactants. In previous work, we showed that the culturing of the orange-pigmented Planococcus sp. CP5-4 isolate increased the evaporation rate of industrial wastewater brine effluent, which we attributed to the orange pigment. This demonstrated the potential application of this bacterium for industrial brine effluent management in evaporation ponds for inland desalination plants. Here we identified a C30-carotenoid biosynthetic gene cluster responsible for pigment biosynthesis in Planococcus sp. CP5-4 through isolation of mutants and genome sequencing. We further compare the core genes of the carotenoid biosynthetic gene clusters identified from different Planococcus species' genomes which grouped into gene cluster families containing BGCs linked to different carotenoid product chemotypes. Lastly, LC-MS analysis of saponified and unsaponified pigment extracts obtained from cultures of Planococcus sp. CP5-4, revealed the structure of the main (predominant) glucosylated C30-carotenoid fatty acid ester produced by Planococcus sp. CP5-4.

RESULTS

Genome sequence comparisons of isolated mutant strains of Planococcus sp. CP5-4 showed deletions of 146 Kb and 3 Kb for the non-pigmented and "yellow" mutants respectively. Eight candidate genes, likely responsible for C30-carotenoid biosynthesis, were identified on the wild-type genome region corresponding to the deleted segment in the non-pigmented mutant. Six of the eight candidate genes formed a biosynthetic gene cluster. A truncation of crtP was responsible for the "yellow" mutant phenotype. Genome annotation revealed that the genes encoded 4,4'-diapolycopene oxygenase (CrtNb), 4,4'- diapolycopen-4-al dehydrogenase (CrtNc), 4,4'-diapophytoene desaturase (CrtN), 4,4'- diaponeurosporene oxygenase (CrtP), glycerol acyltransferase (Agpat), family 2 glucosyl transferase 2 (Gtf2), phytoene/squalene synthase (CrtM), and cytochrome P450 hydroxylase enzymes. Carotenoid analysis showed that a glucosylated C30-carotenoid fatty acid ester, methyl 5-(6-C17:3)-glucosyl-5, 6'-dihydro-apo-4, 4'-lycopenoate was the main carotenoid compound produced by Planococcus sp. CP5-4.

CONCLUSION

We identified and characterized the carotenoid biosynthetic gene cluster and the C30-carotenoid compound produced by Planococcus sp. CP5-4. Mass-spectrometry guided analysis of the saponified and unsaponified pigment extracts showed that methyl 5-glucosyl-5, 6-dihydro-apo-4, 4'-lycopenoate esterified to heptadecatrienoic acid (C17:3). Furthermore, through phylogenetic analysis of the core carotenoid BGCs of Planococcus species we show that various C30-carotenoid product chemotypes, apart from methyl 5-glucosyl-5, 6-dihydro-apo-4, 4'-lycopenoate and 5-glucosyl-4, 4-diaponeurosporen-4'-ol-4-oic acid, may be produced that could offer opportunities for a variety of applications.

Bacterial Carotenoids: Extraction, Characterization, and Applications

Natural carotenoids are secondary metabolites that exhibit antioxidant, anti-inflammatory, and anti-cancer properties. These types of compounds are highly demanded by pharmaceutical, cosmetic, nutraceutical, and food industries, leading to the search for new natural sources of carotenoids. In recent years, the production of carotenoids from bacteria has become of great interest for industrial applications. In addition to carotenoids with C40-skeletons, some bacteria have the ability to synthesize characteristic carotenoids with C30-skeletons. In this regard, a great variety of methodologies for the extraction and identification of bacterial carotenoids has been reported and this is the first review that condenses most of this information. To understand the diversity of carotenoids from bacteria, we present their biosynthetic origin in order to focus on the methodologies employed in their extraction and characterization. Special emphasis has been made on high-performance liquid chromatography-mass spectrometry (HPLC-MS) for the analysis and identification of bacterial carotenoids. We end up this review showing their potential commercial use. This review is proposed as a guide for the identification of these metabolites, which are frequently reported in new bacteria strains.

A review on cyanobacteria cultivation for carbohydrate-based biofuels: Cultivation aspects, polysaccharides accumulation strategies, and biofuels production scenarios

Cyanobacterial biomass has constituted a crucial third and fourth-generation biofuel material, with great potential to synthesize a wide range of metabolites, mainly carbohydrates. Lately, carbohydrate-based biofuels from cyanobacteria, such as bioethanol, biohydrogen, and biobutanol, have attracted attention as a sustainable alternative to petroleum-based products. Cyanobacteria can perform a simple process of saccharification, and extracted carbohydrates can be converted into biofuels with two alternatives; the first one consists of a fermentative process based on bacteria or yeasts, while the second alternative consists of an internal metabolic process of their own in intracellular carbohydrate content, either by the natural or genetic engineered process. This study reviewed carbohydrate-enriched cyanobacterial biomass as feedstock for biofuels. Detailed insights on technical strategies and limitations of cultivation, polysaccharide accumulation strategies for further fermentation process were provided. Advances and challenges in bioethanol, biohydrogen, and biobutanol production by cyanobacteria synthesis and an independent fermentative process are presented. Critical outlook on life-cycle assessment and techno-economical aspects for large-scale application of these technologies were discussed.

Evaluation of potent cyanobacteria species for UV-protecting compound synthesis using bicarbonate-based culture system

The present investigation evaluates the potential of three cyanobacteria species Anabaena cylindrica, Nostoc commune and Synechococcus BDUSM-13 for photo-protecting mycosporine-like amino acids (MAAs) synthesis using bicarbonate-based culture system. Current investigations witnessed noteworthy bicarbonate tolerance of all species (NaHCO3; 0.5, 1 and 2 g L- 1) in terms of their growth rate, chlorophyll content, biomass productivity and carbon fixation ability. Among all strains, Synechococcus BDUSM-13 showed maximum surge in specific growth rate (i.e. 0.72 day-1) at 1 g L-1, productivity (i.e. 0.92 ± 0.06 g day-1 L-1) and chlorophyll content (i.e. 0.09 g L-1) at 2 g day-1 L-1. Synechococcus cells were also has the 0.48 g dw-1 carbon content with highest CO2 fixation rate (i.e. 0.653 g.CO2 mL-1 day-1) at 2 g L-1. Though, they were not able to produce MAAs after long UV-B exposure (i.e. 24 and 48 h). A. cylindrica strain was the most competent species for the bicarbonate-based approach, produced UV-protecting iminomycosporine compound (i.e. shinorine, λ max at 334 ± 2 nm) along with carbon fixation (i.e. 0.49 g CO2 mL-1 day-1) at 2 g L-1 NaHCO3. This suggests the bicarbonate supplementation during cultivation is a promising strategy to increase cellular abundance, biomass productivity and carbon fixation in cyanobacteria. However, UV-B irradiation may cause species-specific differences in the MAAs synthesis to produce UV-protecting compounds.

Production of phycobiliprotein and carotenoid by efficient extraction from Thermosynechococcus sp. CL-1 cultivation in swine wastewater

In this study, the performance of TCL-1 cultivation in swine wastewater was observed under various light intensity, treatment type of swine wastewater, and initial biomass concentration. Furthermore, pigments production (phycobiliprotein and carotenoid), was the main target in this study along with optimum extraction method. Under the cultivation in the anoxic treated swine wastewater (ATSW), highest biomass increment (1.001 ± 0.104 g/L) was achieved with 2 g/L initial biomass concentration and 1,000 µE/m²/s light intensity whereas cultivation in the anoxic and aerobic treated swine wastewater (AATSW) presented better performance on pigments production with the highest production in allophycocyanin which reached 12.07 ± 0.3% dwc. Extraction time and ultrasonication have significant influence on the phycobiliprotein extraction, yet different temperature and incubation time give similar extraction result for β-carotene. Carotenoids production with AATSW cultivation were two times higher than the cultivation in ATSW. However, ammonium-N degradation was performed better in the ATSW cultivation.

Determination of water-soluble vitamins and carotenoids in Brazilian tropical fruits by High Performance Liquid Chromatography

Vitamins are organic compounds essential for normal physiological functioning and they need to be provided in adequate amounts by the diet. They are nutrients mainly associated to fruit consumption, playing an important role in the cellular function, growth and development of individuals. The present study aimed to analyze levels of vitamins B, C and carotenoids of fruits from the agrobiodiversity of Northeastern Brazil, among them cajuí (Anacardium spp), murici (Byrsonima crassifolia (L.) Kunth), pequi (Caryocar coriaceum Wittm.), jenipapo (Genipa americana L.), mangaba (Hancornia speciosa Gomes), bacuri (Platonia insignis Mart.), cajá (Spondias mombin L.), umbu-cajá (Spondias bahiensis P. Carvalho, Van den Berg & M. Machado), umbu (Spondias tuberosa Arruda), pitanga (Eugenia uniflora L.), araçá (Psidium sobralianum Landrum & Proença). The vitamins were quantified using the analytical method High Performance Liquid Chromatography (HPLC). Vitamin B complex levels varied from 0.003 ± 0.01 mg/100 g to 6.107 ± 0.06 mg/100 g. Vitamin C ranged from 0.36 ± 0.06 mg/100 g to 253.92 ± 9.02 mg/100 g. Carotenoid values ranged from 0.12 ± 0.02 μg/100 g to 395.63 ± 113.69 μg/100 g. Thus, the profile of water-soluble vitamins and carotenoids of the fruits analyzed was quantified. Therefore, these fruits can provide varied amounts of vitamins important to human health. However, it is interesting for the individual to consume fruits in a diversified manner, avoiding monotony and thus guaranteeing the daily intake of more nutrients.

Accomplished High-Resolution Metabolomic and Molecular Studies Identify New Carotenoid Biosynthetic Reactions in Cyanobacteria

Cyanobacteria and microalgae are characterized by a rich and varied profile of chlorophyll (8-20 mg/g) and carotenoid (>2.2 mg/g) pigments, being noteworthy material for natural pigment production in the food industry. We propose a systematic workflow that uses high-performance liquid chromatography (HPLC) coupled with high-resolution tandem mass spectrometry in a broadband collision-induced dissociation mode (bbCID) acquisition mode to simultaneously obtain MS and MSⁿ spectra. Metabolomic studies showed for the first time the presence of carotenoids with 5,6-epoxy-groups (5,6-epoxy- and 5,8-furanoid β-cryptoxanthin), carotenoids from the α-branch (5,8-furanoid-2'-3'-didehydro α-cryptoxanthin), and 2'-dehydrodeoxomyxol in cyanobacteria. To support the new findings, an in silico search retrieved the putative sequences of carotenogenic enzymes involved in the corresponding biosynthetic pathways (ZEP, NSY, CrtL-b and CrtR) in the analyzed cyanobacteria species. Consequently, high-throughput metabolomics studies assisted by molecular analysis offer a powerful tool for providing insights into the characterization of bioactive compounds and their metabolism in cyanobacteria and microalgae.

HPLC-PDA-MS/MS as a strategy to characterize and quantify natural pigments from microalgae

Interest in pigment composition of microalgae species is growing as new natural pigments sources are being sought. However, we still have a limited number of species of microalgae exploited to obtain these compounds. Considering these facts, the detailed composition of carotenoids and chlorophylls of two species of green microalgae (Chlorella sorokiniana and Scenedesmus bijuga) were determined for the first time by high-performance liquid chromatography coupled to diode array and mass spectrometry detectors (HPLC-PDA-MS/MS). A total of 17 different carotenoids were separated in all the extracts. Most of the carotenoids present in the two microalgae species are xanthophylls. C. sorokiniana presented 11 carotenoids (1408.46 μg g⁻¹), and S. bijuga showed 16 carotenoids (1195.75 μg g⁻¹). The main carotenoids detected in the two microalgae were all-trans-lutein and all-trans-β-carotene. All-trans-lutein was substantially higher in C. sorokiniana (59.01%), whereas all-trans-β-carotene was detected in higher quantitative values in S. bijuga (13.88%). Seven chlorophyll compounds were identified in both strains with different proportions in each species. Concentrations of chlorophyll representing 7.6% and 10.2% of the composition of the compounds present in the biomass of C. sorokiniana and S. bijuga, respectively. Relevant chlorophyll compounds are reported for the first time in these strains. The data obtained provide significant insights for microalgae pigment composition databases.

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The carotenoids and chlorophylls profile by HPLC-PDA-MS of microalgae is reported.

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Microalgae showed species-specific pigments profiles.

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17 carotenoids and 7 chlorophylls were identified and quantified in details.

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The quantitative profile presented a prevalence of chlorophylls over carotenoids.

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Green microalgae are proposed as an interesting natural source of food pigments.

First Apocarotenoids Profiling of Four Microalgae Strains

Both enzymatic or oxidative carotenoids cleavages can often occur in nature and produce a wide range of bioactive apocarotenoids. Considering that no detailed information is available in the literature regarding the occurrence of apocarotenoids in microalgae species, the aim of this study was to study the extraction and characterization of apocarotenoids in four different microalgae strains: Chlamydomonas sp. CCMP 2294, Tetraselmis chuii SAG 8-6, Nannochloropsis gaditana CCMP 526, and Chlorella sorokiniana NIVA-CHL 176. This was done for the first time using an online method coupling supercritical fluid extraction and supercritical fluid chromatography tandem mass spectrometry. A total of 29 different apocarotenoids, including various apocarotenoid fatty acid esters, were detected: apo-12’-zeaxanthinal, β-apo-12’-carotenal, apo-12-luteinal, and apo-12’-violaxanthal. These were detected in all the investigated strains together with the two apocarotenoid esters, apo-10’-zeaxanthinal-C4:0 and apo-8’-zeaxanthinal-C8:0. The overall extraction and detection time for the apocarotenoids was less than 10 min, including apocarotenoids esters, with an overall analysis time of less than 20 min. Moreover, preliminary quantitative data showed that the β-apo-8’-carotenal content was around 0.8% and 2.4% of the parent carotenoid, in the C. sorokiniana and T. chuii strains, respectively. This methodology could be applied as a selective and efficient method for the apocarotenoids detection.