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BACKGROUND: The drive towards ensuring the sustainability of bioresources has been linked with better valorising primary materials and developing biorefinery pipelines. Seaweeds constitute valuable coastal resources with applications in the bioenergy, biofertiliser, nutrition, pharmaceutical and cosmetic sectors. Owing to the various sought-after metabolites they possess, several seaweed species are commercially exploited throughout Western Europe, including Ireland. Here, four commercially relevant brown (Fucus serratus and Fucus vesiculosus) and red (Chondrus crispus and Mastocarpus stellatus) seaweed species were sampled during a spring tide in July 2021 on moderately exposed shores across three coastal regions in the west of Ireland. RESULTS: Significant regional differences were identified when specimens were analysed for carbohydrates (max. 80.3 µg glucose eq mg-1 DW), proteins (max. 431.3 µg BSA eq. mg-1 DW), lipids (max. 158.6 mg g-1 DW), pigment signature and antioxidant potential. Protein content for F. serratus recorded a twofold difference between northern and southern specimens. The antioxidant potential of F. vesiculosus and M. stellatus returned greater activity compared to F. serratus and C. crispus, respectively. Multivariate analysis showed a clear latitudinal pattern across the three western coastal regions (north, west and south) for both F. vesiculosus and F. serratus. CONCLUSION: F. vesiculosus thalli from the northwest were richer in pigment content while the F. serratus thalli from the northwest were richer in antioxidants. Such biogeographic patterns in the biochemical make-up of seaweeds need consideration for the development of regional integrated aquaculture systems and the optimisation of the biomass content for targeted downstream applications. © 2024 Society of Chemical Industry.
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Antioxidantes , Fucus , Alga Marinha , Alga Marinha/química , Alga Marinha/metabolismo , Antioxidantes/análise , Antioxidantes/química , Fucus/química , Chondrus/química , Irlanda , Europa (Continente) , Lipídeos/análise , Lipídeos/química , Carboidratos/análise , Carboidratos/químicaRESUMO
Phytoplankton and biotoxin monitoring programmes have been implemented in many countries to protect human health and to mitigate the impacts of harmful algal blooms (HABs) on the aquaculture industry. Several amphidomatacean species have been confirmed in Irish coastal waters, including the azaspiracid-producing species Azadinium spinosum and Amphidoma languida. Biogeographic distribution studies have been hampered by the fact that these small, armoured dinoflagellates share remarkably similar morphologies when observed by light microscopy. The recent releases of species-specific molecular detection assays have, in this context, been welcome developments. A survey of the south west and west coasts of Ireland was carried out in August 2017 to investigate the late summer distribution of toxic amphidomataceans and azaspiracid toxins. Azadinium spinosum and Am. languida were detected in 83% of samples in the southwest along the Crease Line and Bantry Bay transects between 20 and 70 m depth, with maximal cell concentrations of 7000 and 470,000 cells/L, respectively. Azaspiracid concentrations were well aligned with the distributions of Az. spinosum and Am. languida, up to 1.1 ng/L and 4.9 ng/L for combined AZA-1, -2, -33, and combined AZA-38, -39, respectively. Although a snapshot in time, this survey provides new insights in the late summer prominence of AZAs and AZA-producing species in the southwest of Ireland, where major shellfish aquaculture operations are located. Results showed a substantial overlap in the distribution of amphidomatacean species in the area and provide valuable baseline information in the context of ongoing monitoring efforts of toxigenic amphidomataceans in the region.
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Dinoflagellida , Compostos de Espiro , Dinoflagellida/genética , Humanos , Irlanda , Toxinas Marinhas , Compostos de Espiro/análiseRESUMO
Diatoms are ubiquitous photosynthetic microorganisms with great potential for biotechnological applications. However, their commercialisation is hampered by production costs, requiring hence optimisation of cultivation methods. Phytohormones are plant growth regulators which may be used to influence physiological processes in microalgae, including diatoms. In this study, the model species Phaeodactylum tricornutum (Phaeodactylaceae) and two Irish isolates of Stauroneis sp. (Stauroneidaceae) and Nitzschia sp. (Bacillariaceae) were grown with varying amounts of the phytohormones indoleacetic acid (IAA), gibberellic acid (GA3), methyl jasmonate (MJ), abscisic acid (ABA) or salicylic acid (SA), and their influence on pigment and fatty acid profiles was monitored. The application of GA3 (200 mg/l) stimulated the growth of P. tricornutum which accumulated 52% more dry biomass compared to the control and concomitantly returned the highest eicosapentaenoic acid (EPA) yield (0.6 mg/l). The highest fucoxanthin yield (0.18 mg/l) was obtained for P. tricornutum cultivated with GA3 (2 mg/l) supplementation. In Stauroneis sp., SA (1 mg/l) had the most positive effect on EPA, the content of which was enhanced up to 45.7 µg/mg (4.6% of total dry weight). The SA (1 mg/l) treatment also boosted carotenogenesis in Nitzschia sp., leading to 1.7- and 14-fold increases in fucoxanthin and ß-carotene compared to the control, respectively. Of note, MJ (0.5 mg/l) increased the EPA content of all diatom species compared to their controls. These results indicate that phytohormone-based treatments can be used to alter the pigment and lipid content of microalgae, which tend to respond in dose- and species-specific manners to individual compounds.Key points⢠Response to phytohormones was investigated in diatoms from distinct families.⢠MJ (0.5 mg/l) caused an increase in EPA cellular content in all three diatoms.⢠Phytohormones mostly caused dose-dependent and species-specific responses.
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Diatomáceas , Microalgas , Suplementos Nutricionais , Ácido Eicosapentaenoico , Ácidos Graxos , Humanos , Reguladores de Crescimento de PlantasRESUMO
Compounds from microalgae such as ω3-fatty acids or carotenoid are commercially exploited within the pharmacology, nutraceutical, or cosmetic sectors. The co-stimulation of several compounds of interest may improve the cost-effectiveness of microalgal biorefinery pipelines. This study focussed on Phaeodactylum tricornutum to investigate the effects on lipogenesis and carotenogenesis of combined stressors, here cold temperature and addition of NaCl salt or the phytohormone abscisic acid, using a two-stage cultivation strategy. Cold stress with NaCl or phytohormone addition increased the neutral lipid content of the biomass (20 to 35%). These treatments also enhanced the proportions of EPA (22% greater than control) in the fatty acid profile. Also, these treatments had a stimulatory effect on carotenogenesis, especially the combination of cold stress with NaCl addition, which returned the highest production of fucoxanthin (33% increase). The gene expression of diacylglycerol acyltransferase (DGAT) and the ω-3 desaturase precursor (PTD15) were enhanced 4- and 16-fold relative to the control, respectively. In addition, zeaxanthin epoxidase 3 (ZEP3), was downregulated at low temperature when combined with abscisic acid. These results highlight the benefits of applying a combination of low temperature and salinity stress, to simultaneously enhance the yields of the valuable metabolites EPA and fucoxanthin in Phaeodactylum tricornutum.
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Diatomáceas , Microalgas , Ácido Abscísico/farmacologia , Ácido Abscísico/metabolismo , Lipogênese , Cloreto de Sódio , Resposta ao Choque Frio , Reguladores de Crescimento de Plantas/metabolismo , Microalgas/metabolismo , Suplementos NutricionaisRESUMO
Microalgae have received growing interest for their capacity to produce bioactive metabolites. This study aimed at characterising the antimicrobial potential of the marine dinoflagellate Amphidinium carterae strain LACW11, isolated from the west of Ireland. Amphidinolides have been identified as cytotoxic polyoxygenated polyketides produced by several Amphidinium species. Phylogenetic inference assigned our strain to Amphidinium carterae subclade III, along with isolates interspersed in different geographic regions. A two-stage extraction and fractionation process of the biomass was carried out. Extracts obtained after stage-1 were tested for bioactivity against bacterial ATCC strains of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa. The stage-2 solid phase extraction provided 16 fractions, which were tested against S. aureus and E. faecalis. Fractions I, J and K yielded minimum inhibitory concentrations between 16 µg/mL and 256 µg/mL for both Gram-positive. A targeted metabolomic approach using UHPLC-HRMS/MS analysis applied on fractions G to J evidenced the presence of amphidinol type compounds AM-A, AM-B, AM-22 and a new derivative dehydroAM-A, with characteristic masses of m/z 1361, 1463, 1667 and 1343, respectively. Combining the results of the biological assays with the targeted metabolomic approach, we could conclude that AM-A and the new derivative dehydroAM-A are responsible for the detected antimicrobial bioactivity.
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Antibacterianos/farmacologia , Organismos Aquáticos/química , Bactérias/crescimento & desenvolvimento , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Dinoflagellida/química , Macrolídeos/farmacologia , Antibacterianos/química , Organismos Aquáticos/crescimento & desenvolvimento , Compostos Bicíclicos Heterocíclicos com Pontes/química , Dinoflagellida/crescimento & desenvolvimento , Macrolídeos/químicaRESUMO
Tailoring spectral quality during microalgal cultivation can provide a means to increase productivity and enhance biomass composition for downstream biorefinery. Five microalgae strains from three distinct lineages were cultivated under varying spectral intensities and qualities to establish their effects on pigments and carbon allocation. Light intensity significantly impacted pigment yields and carbon allocation in all strains, while the effects of spectral quality were mostly species-specific. High light conditions induced chlorophyll photoacclimation and resulted in an increase in xanthophyll cycle pigments in three of the five strains. High-intensity blue LEDs increased zeaxanthin tenfold in Rhodella sp. APOT_15 relative to medium or low light conditions. White light however was optimal for phycobiliprotein content (11.2 mg mL-1) for all tested light intensities in this strain. The highest xanthophyll pigment yields for the Chlorophyceae were associated with medium-intensity blue and green lights for Brachiomonas submarina APSW_11 (5.6 mg g-1 lutein and 2.0 mg g-1 zeaxanthin) and Kirchneriella aperta DMGFW_21 (1.5 mg g-1 lutein and 1 mg g-1 zeaxanthin), respectively. The highest fucoxanthin content in both Heterokontophyceae strains (2.0 mg g-1) was associated with medium and high white light for Stauroneis sp. LACW_24 and Phaeothamnion sp. LACW_34, respectively. This research provides insights into the application of LEDs to influence microalgal physiology, highlighting the roles of low light on lipid metabolism in Rhodella sp. APOT_15, of blue and green lights for carotenogenesis in Chlorophyceae and red light-induced photoacclimation in diatoms.
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Aclimatação/efeitos da radiação , Carbono/metabolismo , Luz , Microalgas/metabolismo , Microalgas/efeitos da radiação , Pigmentos Biológicos/metabolismo , Clorofíceas/metabolismo , Clorofila A/metabolismo , Microalgas/crescimento & desenvolvimento , Ficobiliproteínas/metabolismo , Rodófitas/crescimento & desenvolvimento , Rodófitas/metabolismo , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Landfill leachate treatment is an ongoing challenge in the wastewater management of existing sanitary landfill sites due to the complex nature of leachates and their heavy pollutant load. There is a continuous interest in treatment biotechnologies with expected added benefits for resource recovery; microalgal bioremediation is seen as promising in this regard. Toxicity reduction of landfill leachate subsequent to phycoremediation was investigated in this study. The treatment eventuated from the growth of the ammonia tolerant microalgal strain Chlamydomonas sp. SW15aRL using a N:P ratio adjustment in diluted leachate for facilitating the process. Toxicity tests ranging over a number of trophic levels were applied, including bacterial-yeast (MARA), protistean (microalgae growth inhibition test), crustacean (daphnia, rotifer) and higher plant (monocot, dicot) assays. Ammonia nitrogen in the diluted landfill leachate containing up to 158mgl-1 NH4+-N (60% dilution of the original) was reduced by 83% during the microalgal treatment. Testing prior to remediation indicated the highest toxicity in the crustacean assays Daphnia magna and Brachionus calyciflorus with EC50s at 24h of ~ 35% and 40% leachate dilution, respectively. A major reduction in toxicity was achieved with both bioassays post microalgal treatment with effects well below the EC20s. The microalgae inhibition test on the other hand indicated increased stimulation of growth after treatment as a result of toxicity reduction but also the presence of residual nutrients. Several concurrent processes of both biotic and abiotic natures contributed to pollutant reduction during the treatment. Modifying phosphate dosage especially seems to require further attention. As a by-product of the remediation process, up to 1.2gl-1 of microalgal biomass was obtained with ~ 18% DW lipid content.
Assuntos
Chlamydomonas/metabolismo , Microalgas/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Animais , Biodegradação Ambiental , Chlamydomonas/crescimento & desenvolvimento , Daphnia/efeitos dos fármacos , Monitoramento Ambiental , Irlanda , Microalgas/crescimento & desenvolvimento , Rotíferos/efeitos dos fármacos , Testes de ToxicidadeRESUMO
Extracellular vesicles (EVs) are membrane-enclosed bio-nanoparticles secreted by cells and naturally evolved to transport various bioactive molecules between cells and even organisms. These cellular objects are considered one of the most promising bio-nanovehicles for the delivery of native and exogenous molecular cargo. However, many challenges with state-of-the-art EV-based candidates as drug carriers still exist, including issues with scalability, batch-to-batch reproducibility, and cost-sustainability of the final therapeutic formulation. Microalgal extracellular vesicles, which we named nanoalgosomes, are naturally released by various microalgal species. Here, we evaluate the innate biological properties of nanoalgosomes derived from cultures of the marine microalgae Tetraselmis chuii, using an optimized manufacturing protocol. Our investigation of nanoalgosome biocompatibility in preclinical models includes toxicological analyses, using the invertebrate model organism Caenorhabditis elegans, hematological and immunological evaluations ex vivo and in mice. We evaluate nanoalgosome cellular uptake mechanisms in C. elegans at cellular and subcellular levels, and study their biodistribution in mice with accurate space-time resolution. Further examination highlights the antioxidant and anti-inflammatory bioactivities of nanoalgosomes. This holistic approach to nanoalgosome functional characterization demonstrates that they are biocompatible and innate bioactive effectors with unique bone tropism. These findings suggest that nanoalgosomes have significant potential for future therapeutic applications.
Assuntos
Anti-Inflamatórios , Antioxidantes , Vesículas Extracelulares , Microalgas , Vesículas Extracelulares/metabolismo , Animais , Microalgas/metabolismo , Camundongos , Anti-Inflamatórios/farmacologia , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Caenorhabditis elegans/metabolismo , Materiais Biocompatíveis/química , Clorófitas/metabolismo , Osso e Ossos/metabolismo , TropismoRESUMO
The sourcing of novel bioactive compounds from bioresources has become a sustainability priority for several industrial sectors. Reliable methods are hence needed for the screening and identification of desired molecules in complex extracts. As such, phenolic compounds have attracted increasing interests due to their antioxidant potential. Here, a HPLC-UV based method was developed for the determination of phenolic compounds using a monolithic column. This allowed the separation of 23 phenolic compounds within 11 min. The method was ground proofed in terms of chromatographic parameters and applied to identify polyphenols in extracts of blueberries, basil and marine microalgae. The dominant polyphenols in blueberries and basil were chlorogenic acid (26.0 mg. kg -1) and kaempferol (61.4 mg. kg -1), respectively, while the microalgae used only contained trace amounts of polyphenols. This study demonstrates the value of our new HPLC method to rapidly screen extracts and identify polyphenols from biological matrices.
Assuntos
Fenóis , Polifenóis , Cromatografia Líquida de Alta Pressão , Ácido Clorogênico , Extratos VegetaisRESUMO
There has been increasing demands worldwide for bioactive compounds of natural origins, especially for the nutraceutical and food-supplement sectors. In this context, microalgae are viewed as sustainable sources of molecules with an array of health benefits. For instance, astaxanthin is a xanthophyll pigment with powerful antioxidant capacity produced by microalgae such as the chlorophyte Haematococcus sp., which is regarded as the most suitable organism for the mass production of this pigment. In this study, three Haematococcus sp. strains were cultivated using a batch mode under favourable conditions to promote vegetative growth. Their environment was altered in a second phase using a higher and constant illumination regime combined with either exposure to blue LED light, an osmotic shock (with NaCl addition) or supplementation with a phytohormone (gibberellic acid, GA3), a plant extract (ginger), an herbicide (molinate) or an oxidant reagent (hydrogen peroxide). The effects of these stressors were evaluated in terms of antioxidant response and astaxanthin and ß-carotene accumulation. Overall, strain CCAP 34/7 returned the highest Trolox Equivalent Antioxidant Capacity (TEAC) response (14.1-49.1 µmoL Trolox eq. g- 1 of DW), while the highest antioxidant response with the Folin-Ciocalteu (FC) was obtained for strain RPFW01 (62.5-155 µmoL Trolox eq. g- 1 of DW). The highest ß-ß-carotene content was found in strain LAFW15 when supplemented with the ginger extract (4.8 mg. g- 1). Strain RPFW01 exposed to blue light returned the highest astaxanthin yield (2.8 mg. g- 1), 5-fold that of strain CCAP 34/7 on average. This study documents the importance of screening several strains when prospecting for species with potential to produce high-value metabolites. It highlights that strain-specific responses can ensue from exposure of cells to a variety of stressors, which is important for the adequate tailoring of a biorefinery pipeline.
Assuntos
Clorofíceas , Clorófitas , Herbicidas , Microalgas , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Carotenoides/metabolismo , Clorofíceas/metabolismo , Peróxido de Hidrogênio , Microalgas/metabolismo , Oxidantes/metabolismo , Extratos Vegetais/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Cloreto de Sódio , Xantofilas/metabolismo , beta Caroteno/metabolismoRESUMO
There have been growing interests in microalgal biotechnology for the biorefining of bioactive compounds such as carotenoid pigments, ω-3 fatty acids, antioxidants or antimicrobials for sectoral applications in the pharmacology, nutraceutical and cosmetic fields. This study focused on the unicellular marine rhodophyte Porphyridium purpureum CCAP 1380/1 A, which was cultivated via a two-stage batch growth mode for 10 days using hydrogen peroxide (H2O2), the phytohormone methyl jasmonate (MJ) and three plant extracts (Passiflora incarnata, Panax ginseng and Valeriana officinalis). The microalgal biomass was then analysed for its protein, phycoerythtin, carbohydrate and pigment composition together with its pigment content and antioxidant activity. Of note, MJ increased the protein and phycoerythtin content (up to 225 µg BSA eq./mg DW and 15 mg/ml, respectively) while both the MJ and H2O2 treatments increased carotenoid pigment yields (ß-carotene and zeaxanthin, up to 5 and 4 mg/g, respectively). Carbohydrates were enhanced â¼10 fold by the Valeriana officinalis treatment (up 192 µg starch eq./mg). Overall, neutral lipids and antioxidants were mostly negatively affected by the plant extracts. The greatest antioxidant activity registered was obtained with the H2O2 treatment (15 µmol Trolox eq./g DW with TEAC assay). P. purpureum contains multiple valuable compounds of commercial interest. These results indicate that they can be favorably modulated using specific cultivation regimes and chemical enhancers, thereby facilitating the exploitation of the biomass by applying a suitable co-refinery pipeline.
Assuntos
Porphyridium , Antioxidantes , Peróxido de Hidrogênio , Extratos Vegetais/farmacologiaRESUMO
Extracellular vesicles (EVs) play a crucial role as potent signal transducers among cells, with the potential to operate cross-species and cross-kingdom communication. Nanoalgosomes are a subtype of EVs recently identified and isolated from microalgae. Microalgae represent a natural bioresource with the capacity to produce several secondary metabolites with a broad range of biological activities and commercial applications. The present study highlights the upstream and downstream processes required for the scalable production of nanoalgosomes from cultures of the marine microalgae Tetraselmis chuii. Different technical parameters, protocols, and conditions were assessed to improve EVs isolation by tangential flow filtration (TFF), aiming to enhance sample purity and yield. The optimization of the overall bioprocess was enhanced by quality control checks operated through robust biophysical and biochemical characterizations. Further, we showed the possibility of recycling by TFF microalgae cells post-EVs isolation for multiple EV production cycles. The present results highlight the potential of nanoalgosome production as a scalable, cost-effective bioprocess suitable for diverse scientific and industrial exploitations.
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Extracellular vesicles (EVs) are lipid membrane nano-sized vesicles secreted by various cell types for intercellular communication, found in all kingdoms of life. Nanoalgosomes are a subtype of EVs derived from microalgae with a sustainable biotechnological potential. To explore the uptake, distribution and persistence of nanoalgosomes in cells and living organisms, we separated them from a culture of the chlorophyte Tetraselmis chuii cells by tangential flow filtration (TFF), labelled them with different lipophilic dyes and characterized their biophysical attributes. Then we studied the cellular uptake of labelled nanoalgosomes in human cells and in C. elegans, demonstrating that they enter the cells through an energy dependent mechanism and are localized in the cytoplasm of specific cells, where they persist for days. Our data confirm that nanoalgosomes are actively uptaken in vitro by human cells and in vivo by C. elegans cells, supporting their exploitation as potential nanocarriers of bioactive compounds for theranostic applications.
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Extracellular vesicles (EVs) are emerging as promising diagnostic and therapeutic tools for a variety of diseases. The characterization of EVs requires a series of orthogonal techniques that are overall time- and material-consuming. Here, a microfluidic device is presented that exploits the combination of diffusion sizing and multiwavelength fluorescence detection to simultaneously provide information on EV size, concentration, and composition. The latter is achieved with the nonspecific staining of lipids and proteins combined with the specific staining of EV markers such as EV-associated tetraspanins via antibodies. The device can be operated as a single-step immunoassay thanks to the integrated separation and quantification of free and EV-bound fluorophores. This microfluidic technique is capable of detecting and quantifying components associated to EV subtypes and impurities and thus to measure EV purity in a time scale of minutes, requiring less than 5 µL of sample and minimal sample handling before the analysis. Moreover, the analysis is performed directly in solution without immobilization steps. Therefore, this method can accelerate screening of EV samples and aid the evaluation of sample reproducibility, representing an important complementary tool to the current array of biophysical methods for EV characterization, particularly valuable for instance for bioprocess development.
Assuntos
Vesículas Extracelulares , Microfluídica , Biomarcadores/metabolismo , Vesículas Extracelulares/metabolismo , Dispositivos Lab-On-A-Chip , Reprodutibilidade dos TestesRESUMO
Extracellular vesicles (EVs) large-scale production is a crucial point for the translation of EVs from discovery to application of EV-based products. In October 2021, the International Society for Extracellular Vesicles (ISEV), along with support by the FET-OPEN projects, "The Extracellular Vesicle Foundry" (evFOUNDRY) and "Extracellular vesicles from a natural source for tailor-made nanomaterials" (VES4US), organized a workshop entitled "massivEVs" to discuss the potential challenges for translation of EV-based products. This report gives an overview of the topics discussed during "massivEVs", the most important points raised, and the points of consensus reached after discussion among academia and industry representatives. Overall, the review of the existing EV manufacturing, upscaling challenges and directions for their resolution highlighted in the workshop painted an optimistic future for the expanding EV field.
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There has been an increasing drive toward better valorising raw biological materials in the context of the sustainability of bio-based industries and the circular economy. As such, microalgae hold the ability to biosynthesise valuable metabolites, which are sought after within the bioenergy, pharmaceuticals, cosmetics or nutrition sectors. Owing to their bioactivities, the xanthophyll pigment fucoxanthin and the omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) have fostered increasing interests in terms of sustainably refining them from natural sources, such as microalgae. Together with the suitability of individual species to industrial cultivation, a key challenge resides in optimizing the yields of these compounds within the microalgal biomass they are retrieved from. The marine diatom Stauroneis sp. LACW24 was batch cultivated into its stationary phase of growth prior to being subjected at high cell density (1 × 106 cells mL-1 ) to seven different regimes of light exposure in replenished medium and under nutritional limitation (silica and nitrate) for 12 days. The highest EPA proportions and yields were obtained under blue LED in f/2 medium (16.5% and 4.8 mg g-1 , respectively), double the values obtained under red LED illumination. The fucoxanthin yield was the highest when cells were subjected to blue LEDs (5.9 mg g-1 ), a fourfold increase compared to the nitrogen-limited treatment under white LEDs. These results indicate that a two-stage approach to the batch cultivation of this diatom can be used for enhancing the production of the high-value metabolites fucoxanthin and EPA post-stationary phase.
Assuntos
Técnicas de Cultura de Células/métodos , Diatomáceas , Ácido Eicosapentaenoico/metabolismo , Xantofilas/metabolismo , Diatomáceas/metabolismo , Diatomáceas/efeitos da radiaçãoRESUMO
The diatom Stauroneis sp. was previously identified as a promising source of fucoxanthin and omega-3 oils. Methyl jasmonate (MJ) supplementation is known to enhance metabolite yields in this species without impacting on growth or photosynthesis. Therefore, a label-free proteomics approach was undertaken to further evaluate the functional role of MJ on the diatom's physiology. Of the twenty cultivation regimes were screened, Uf/2 medium with green+white LED's induced the greatest metabolic response when exposed to 10 µM MJ treatment. These conditions significantly enhanced the pigment and total cellular lipids contents. The increase in fucoxanthin correlating with a 20% increase in Trolox reducing equivalent in the total antioxidant assay, indicating a non-enzymatic antioxidant role of fucoxanthin to mitigate the detrimental effects of a redox imbalance within chloroplasts. The proteomics identified 197 proteins up-regulated 48 h after MJ exposure including cell signalling cascades, photosynthetic processes, carbohydrate metabolism, lipid biosynthesis and chloroplast biogenesis. MJ strengthened the dark reactions of photosynthesis to support growth and metabolite fluxes. The MJ-induced ER stress protein triggered lipid body production, facilitating metabolite turnover and trafficking between cellular organelles. Plastid terminal oxidase and glutamate 1-semialdehyde 2,1-aminomutase may act as MJ-induced ROS responsive regulatory switch to support chloroplast biosynthesis. SIGNIFICANCE STATEMENT: Phytohormones represents a promising tool to enhance the high-value metabolite yields in plants and algae, however little is known of the role of methyl jasmonate in diatoms at a molecular level. A shotgun proteomics approach was undertaken to determine the influence of MJ on the diatom's cellular physiology in the marine diatom Stauroneis sp., revealing a signal transduction cascade leading to increased lipid and pigment content and identified promising targets for genetic engineering.
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Diatomáceas , Acetatos , Biomassa , Ciclopentanos , Oxilipinas/farmacologia , ProteomaRESUMO
There have been growing interests in the biorefining of bioactive compounds from marine microalgae, including pigments, omega-3 fatty acids or antioxidants for use in the nutraceutical and cosmetic sectors. This study focused on the comparative responses of five marine microalgal species from different lineages, including the dinoflagellate Amphidinium carterae, chlorophyte Brachiomonas submarina, diatom Stauroneis sp., haptophyte Diacronema sp. and rhodophyte Rhodella violacea, to exposure during their batch growth to hydrogen peroxide (H2O2). A. carterae returned an enhanced signal with the DPPH assay (8.8 µmol Trolox eq/g DW) when exposed to H2O2, which was associated with reduced pigment yields and increased proportions in saturated C16 and C18 fatty acids. B. submarina showed enhanced antioxidant response upon exposure to H2O2 with the DPPH assay (10 µmol Trolox eq/g DW), a threefold decrease in lutein (from 2.3 to 0.8 mg/g) but a twofold increase in chlorophyll b (up to 30.0 mg/g). Stauroneis sp. showed a downward response for the antioxidant assays, but its pigment yields did not vary significantly from the control. Diacronema sp. showed reduced antioxidant response and fucoxanthin content (from 4.0 to 0.2 mg/g) when exposed to 0.5 mM H2O2. R. violacea exposed to H2O2 returned enhanced antioxidant activity and proportions of EPA but was not significantly impacted in terms of pigment content. Results indicate that H2O2 can be used to induce stress and initiate metabolic changes in microalgae. The responses were however species-specific, which would require further dosage optimisation to modulate the yields of specific metabolites in individual species.
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Peróxido de Hidrogênio/farmacologia , Microalgas/metabolismo , Estresse Oxidativo/efeitos dos fármacosRESUMO
Microalgae constitute a heterogeneous and diverse range of organisms capable of accumulating bioactive metabolites, making them promising feedstock for applications in the nutraceutical, functional food, animal feed, biofertilisation or biofuel sectors. There has been renewed interest in recent times in natural sources of antioxidants, particularly as health products and preserving agents. Microalgae strains isolated from aquatic habitats in Ireland were successfully brought into culture. The 91 strains were grown phototrophically in nutrient-enriched media to generate biomass, which was harvested and assessed for antioxidant potential. Extracts were screened for antioxidant activity using a modified volumetric Trolox-ABTS assay and the Folin-Ciocalteu method. Two heterokont marine strains of interest were further studied to ascertain variations in antioxidant capacity across different stages of batch culture growth. The antioxidant activity of extracts of bacillariophyte cf. Stauroneis sp. LACW24 and ocrophyte cf. Phaeothamnion sp. LACW34 increased during growth with a maximum being observed during the late stationary or early death phase (2.5- to 8-fold increases between days 20 and 27). Strains LACW24 and LACW34 contained 5.9 and 3.0 mg g-1 (DW) of the xanthophyll fucoxanthin, respectively. Extracts of strains also showed no cytotoxicity towards mouse cell lines. These results highlight the potential of these strains for biomass valorisation and cultivation upscaling and to be further considered as part of ongoing bioprospecting efforts towards identifying novel species to join the relatively narrow range of commercially exploited marine microalgae species.
Assuntos
Antioxidantes/metabolismo , Biomassa , Bioprospecção , Microalgas/crescimento & desenvolvimento , Estramenópilas/crescimento & desenvolvimento , Microbiologia da ÁguaRESUMO
Cellular, inter-organismal and cross kingdom communication via extracellular vesicles (EVs) is intensively studied in basic science with high expectation for a large variety of bio-technological applications. EVs intrinsically possess many attributes of a drug delivery vehicle. Beyond the implications for basic cell biology, academic and industrial interests in EVs have increased in the last few years. Microalgae constitute sustainable and renewable sources of bioactive compounds with a range of sectoral applications, including the formulation of health supplements, cosmetic products and food ingredients. Here we describe a newly discovered subtype of EVs derived from microalgae, which we named nanoalgosomes. We isolated these extracellular nano-objects from cultures of microalgal strains, including the marine photosynthetic chlorophyte Tetraselmis chuii, using differential ultracentrifugation or tangential flow fractionation and focusing on the nanosized small EVs (sEVs). We explore different biochemical and physical properties and we show that nanoalgosomes are efficiently taken up by mammalian cell lines, confirming the cross kingdom communication potential of EVs. This is the first detailed description of such membranous nanovesicles from microalgae. With respect to EVs isolated from other organisms, nanoalgosomes present several advantages in that microalgae are a renewable and sustainable natural source, which could easily be scalable in terms of nanoalgosome production.