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1.
Aquat Toxicol ; 223: 105485, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32353662

RESUMO

Even though HPLC-MS is commonly used to quantify the toxin content of Ostreopsis spp. cells, there is a need to develop easy-to-use toxicological tests to set thresholds during Ostreopsis spp. blooms. The crustacean Artemia has been widely used to evaluate the presence and toxicity of chemicals and biological contaminants and we anticipated that it could also be useful to test Ostreopsis spp. toxicity. Its relevance was first assessed by investigating the variability of the toxic effects among Ostreopsis spp. strains and throughout the dinoflagellate life cycle in combination with chemical analyses of the toxinic content by UHPLC-HRMS. After testing the toxicity of fractions prepared from Ostreopsis spp. cells, the known ova- and paly-toxins were not the only toxic metabolites to Artemia franciscana, indicating that other toxic compounds synthesized by Ostreopsis spp. still remain to be identified. To extend the bioassay to in situ monitoring, the toxicity of the benthic microalgal consortium was tested during a natural bloom of Ostreopsis cf. ovata in the NW Mediterranean Sea. The results highlight the accuracy and sensitivity of the ecotoxicological assay with Artemia franciscana to assess the toxicity of Ostreopsis spp. blooms.


Assuntos
Artemia/efeitos dos fármacos , Dinoflagelados/efeitos dos fármacos , Monitoramento Ambiental/métodos , Microalgas/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Artemia/química , Bioensaio , Dinoflagelados/química , Espectrometria de Massas , Mar Mediterrâneo , Microalgas/química
2.
Poult Sci ; 99(3): 1734-1743, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32115040

RESUMO

This study was conducted to investigate the comparative effects of dietary supplementation with microalgae oil or fish oil on fatty acid composition, sensory quality, and overall acceptability of table eggs. A total of six hundred thirty, 30-week-old, Hy-Line Brown laying hens were allocated to 7 dietary treatments. Layers were fed with a control diet or the control diet supplemented with graded levels of docosahexaenoic acid (DHA; 1.25, 2.50, and 5.00 mg/g feed) derived from microalgae oil or fish oil. The feeding trial lasted 10 wk. Enrichment of eggs with DHA by dietary supplementation with microalgae oil or fish oil enhanced yolk DHA and total n-3 polyunsaturated fatty acid (PUFA) enrichment and reduced n-6-to-n-3 ratio in a dose-response manner, whereas the efficiency decreased (P < 0.05). The overall efficiency of DHA incorporation into eggs was similar for the 2 sources (P > 0.05). In comparison with fish oil, dietary microalgae oil supplementation resulted in higher scores for egg flavor and overall acceptability, both of which declined linearly in response to DHA supplementation (P < 0.05). Among the aroma and flavor characteristics, fishy aroma and flavor scores increased linearly and quadratically (P < 0.05) in response to dietary DHA supplementation, and egg aroma and flavor and milky flavor scores decreased linearly (P < 0.05). The results from partial least squares analysis showed that fishy flavor and aroma were closely associated with DHA, α-linolenic acid, and total n-3 PUFA, and oleic acid, arachidonic acid, and dihomo-gamma-linolenic acid were more related to egg aroma and flavor. The results suggested that microalgae oil would be more promising for egg DHA enrichment owing to better sensory quality of the resultant eggs.


Assuntos
Ração Animal/análise , Ovos/análise , Óleos de Peixe , Microalgas/química , Animais , Galinhas , Dieta/veterinária , Ácidos Docosa-Hexaenoicos , Ácidos Graxos/análise , Feminino , Paladar
3.
Food Chem ; 320: 126627, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32213421

RESUMO

For the last two decades there has been a rise in awareness about the general low dietary intake of vitamin D3. Fish have the highest natural content of vitamin D3, which is suggested to originate from zooplankton and microalgae. However there are no studies reporting which microalgal species may be the source of vitamin D3. In this study, four selected microalgal species were cultivated during exposure of artificial UVB. The effect of UVB dose on the growth and biochemical composition of the cells (vitamin D3, PUFAs and carotenoids) was evaluated. Of the four species, exclusively Nannochloropsis oceanica was able to produce vitamin D3 (up to 1 ± 0.3 µg/g DM), and production was significantly enhanced by increasing the dose of the UVB. These findings suggest that N.oceanica exposed to artificial UVB could be used as a new natural source of vitamin D3, either as direct source or through animal feed.


Assuntos
Produtos Biológicos/química , Colecalciferol/análise , Microalgas/química , Estramenópilas/química
4.
J Food Sci ; 85(4): 998-1006, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32154918

RESUMO

Ellagic acid (EA), a naturally occurring bioactive phenolic compound largely found in pomegranate, exhibits significant health benefits due to its antioxidant, antimutagenic, and even anticancerogenic properties. The present work aimed to microencapsulate EA extracted from pomegranate peels. To improve the stability of EA, microencapsulation was applied with Spirulina as a coating material. For this purpose, ethanolic extracts obtained from pomegranate peels were used for microencapsulation. Response surface methodology combined with a three-level, three-variable Box-Behnken design (BBD) was applied to obtain optimum microencapsulation. The microparticles obtained under the optimized encapsulation conditions were further characterized by FT-IR and SEM. The results confirmed the encapsulation of EA in Spirulina cells. Then, the optimum microparticles were used in an in vitro release study. The results of the in vitro digestion with simulated gastrointestinal fluids could help to determine the content and biological activity of EA. In this study, the effect of encapsulation on the release properties of EA during simulated gastrointestinal digestion was also evaluated. HPLC-DAD analysis and the Folin-Ciocalteu and ABTS methods were helpful for characterization of EA in the simulated fluids. The release profile of EA indicated that in simulated intestinal fluid, the release was faster than that in gastric fluid. PRACTICAL APPLICATION: This study describes the microencapsulation of ethanolic extracts of pomegranate peel (PP) in Spirulina. This application has been performed to improve the stability and bioavailability of EA in the extracts. Optimum microencapsulation was obtained by response surface methodology with BBD. After the characterization of the obtained optimum Spirulina/EA mixture by FT-IR and SEM, an in vitro release study was conducted for stability research. The results will guide other researchers working on the determination of the content and biological activity of EA and on optimizing the microencapsulation process.


Assuntos
Ácido Elágico/química , Ácido Elágico/metabolismo , Microalgas/química , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Romã (Fruta)/química , Antioxidantes/química , Antioxidantes/metabolismo , Digestão , Composição de Medicamentos , Frutas/química , Trato Gastrointestinal/metabolismo , Humanos , Cinética , Modelos Biológicos , Fenóis/química , Fenóis/metabolismo , Romã (Fruta)/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Resíduos/análise
5.
Ecotoxicol Environ Saf ; 195: 110488, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32200143

RESUMO

Effect of water accommodated fractions (WAF) of #180 fuel oil on fixed carbon and nitrogen in microalgae was studied by stable isotopes. Platymonas helgolandica, Heterosigma akashiwo and Nitzschia closterium were exposed to five WAF concentrations for 96 h. The δ13C value of microalgae was significantly lower than that of the control group, indicated that carbon was limited in the WAF concentrations. The δ13C value of microalgae appeared peak valley at 48 h in control group, corresponding to the enhanced capacity in carbon fixation during microalgae photosynthesis. The physiological acclimation capacity of microalgae was revealed by the occurrence time when the δ13C value was in peak valley, and thus the physiological acclimation capacity of microalgae decreased in the order of Nitzschia closterium > Heterosigma akashiwo > Platymonas helgolandica. Principal component analysis (PCA) were applied to the δ13C value in order to verify the "hormesis" phenomenon in microalgae. The δ13C value could discriminate between stimulatory effects at low doses and inhibitory effects at high doses. In addition, the present study also investigated the effect of the nitrogen on microalgae growth. Because microalgae could still absorb the NO3-N and release of NO2-N and NH4-N in present study, the nitrogen cycle in microalgae was in the equilibrium status. The δ15N value in microalgae exhibited no obvious change with the increasing of WAF concentrations at the same time. However, due to the enrichment of nitrogen, the δ15N value first increased gradually with the time and finally was stable. Overall, the fractionation of carbon and nitrogen stable isotopes illustrated that the effect of carbon on the growth of microalgae was more prominent than nitrogen. Stable isotopes was used to investigate the influence of WAF on fixed carbon and nitrogen in microalgae growth, providing a fundamental theoretical guidance for risk assessment of marine ecological environment.


Assuntos
Carbono/análise , Óleos Combustíveis/toxicidade , Microalgas/efeitos dos fármacos , Nitrogênio/análise , Poluentes Químicos da Água/toxicidade , Ciclo do Carbono/efeitos dos fármacos , Isótopos de Carbono/análise , Clorófitas/química , Clorófitas/efeitos dos fármacos , Clorófitas/crescimento & desenvolvimento , Diatomáceas/química , Diatomáceas/efeitos dos fármacos , Diatomáceas/crescimento & desenvolvimento , Microalgas/química , Microalgas/crescimento & desenvolvimento , Isótopos de Nitrogênio/análise , Fotossíntese/efeitos dos fármacos , Estramenópilas/química , Estramenópilas/efeitos dos fármacos , Estramenópilas/crescimento & desenvolvimento , Água/química , Poluentes Químicos da Água/química
6.
Rev Environ Health ; 35(2): 173-188, 2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32134737

RESUMO

According to the report of the renewable energy policy network for the 21st century published in 2014, biodiesel and bioethanol are the most used biofuels and are responsible for transportation worldwide. Biodiesel specially has shown an increase in production globally by 15 times by volume from 2002 to 2012. Promising feedstock of biodiesel are cyanobacteria and microalgae as they possess a shorter cultivation time (4 fold lesser) and high oil content (10 fold higher) than corn, jatropha and soybean (conventional oil-producing territorial plants). Various valuable natural chemicals are also produced from these organisms including food supplements such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), pigments, and vitamins. Additionally, cellular components of microalgae and cyanobacteria are connected with therapeutic characteristics such as anti-inflammatory, antioxidant, antiviral and immune stimulating. Commercialization of algal biodiesel (or other products) can be achieved by isolating and identifying the high-yielding strains that possess a faster growth rate. Indigenous strains can be genetically engineered into high-yielding transgenic strains. The present article discusses about the use of nanotechnology and genetic engineering approach for improved lipid accumulation in microalgae for biodiesel production.


Assuntos
Biocombustíveis , Química Verde/métodos , Microalgas/química , Biocombustíveis/microbiologia
7.
Poult Sci ; 99(2): 1038-1051, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32036961

RESUMO

There is limited information on feeding egg-type chick breeders n-3 polyunsaturated fatty acids (PUFA) and its impact on hatching egg quality and embryonic fatty acid (FA) utilization. We investigated the effects of feeding brown and white egg-type chick breeders diets containing sources of n-3 PUFA on egg composition, apparent embryonic FA utilization, and intestinal FA transporter in hatchlings. Twenty-six-week-old ISA brown and Shaver white breeders were fed either 1) control (CON); 2) CON + 1% of microalgae (DMA, Aurantiochytrium limacinum) fermentation product, as a source of docosahexaenoic acid (DHA); or 3) CON + 2.60% of coextruded full-fat flaxseed and pulse mixture (FFF, 1:1 wt/wt) as a source of α-linolenic acid (ALA). Test diets had similar total n-3 and n-6:n-3 ratio. Eggs were hatched, and residual yolk (RY) samples taken for FA analyses. Apparent embryonic FA utilization was calculated by subtracting concentration of FA in RY from concentration of FA in yolk before incubation. There was an interaction between strains and diets (P < 0.05) on DHA in phospholipid and triglyceride fractions of yolk. Both n-3 PUFA sources increased DHA to a greater extent in Shaver white than in ISA brown. The interactive effect of strains and diets (P = 0.019) on embryonic utilization of ALA was such that DMA and FFF reduced ALA utilization, and this pattern was more prevalent in Shaver white birds than in ISA brown birds. There was no interaction between strains and diets on DHA utilization (P > 0.05). Embryos from hens fed n-3 PUFA sources used less total FA in phospholipid fraction (P < 0.001), and they preferentially used more DHA than CON embryos. Shaver white embryos used more (P < 0.05) ALA and DHA than ISA brown embryos. Although data suggested Shaver white had higher propensity of depositing DHA than ISA brown, irrespective of strain, feeding n-3 PUFA modified embryonic pattern of FA utilization toward utilization of DHA.


Assuntos
Embrião de Galinha/metabolismo , Galinhas/metabolismo , Ácido Eicosapentaenoico/metabolismo , Microalgas/química , Ração Animal/análise , Animais , Dieta/veterinária , Suplementos Nutricionais/análise , Ácido Eicosapentaenoico/administração & dosagem , Proteínas de Transporte de Ácido Graxo/metabolismo , Feminino , Fígado/química , Malondialdeído/metabolismo , Óvulo/química , Óvulo/efeitos dos fármacos , Estramenópilas/química
8.
Mar Drugs ; 18(2)2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-32059424

RESUMO

One of the essential fatty acids with therapeutic impacts on human health is known to be omega-3 polyunsaturated fatty acids (PUFA). More lately, ionic liquids (ILs) have received significant attention among scientists in overcoming the disadvantages of traditional solvents in biomass lipid extraction. However, the large pool of cations and anions possibly accessible will lead to a growing number of innovatively synthesized ILs. Nevertheless, the exhaustive measurement of all these systems is economically impractical. The conductive screening model for real solvents (COSMO-RS) is considered a precious approach with the availability of a few models to predict the characteristics of ILs. This work introduces the estimate of capacity values at infinite dilution for a range of ILs using COSMO-RS software as part of solid-liquid extraction. This favorable outcome presented that the capacity values of the IL molecules are extremely dependent on both anions and cations. Among the 352 combinations of cation/anion tested, short alkyl chain cations coupled with inorganic anions were found to be most efficient and therefore superior in the extraction method. Sulphate-, chloride-, and bromide-based ILs were found to have higher extraction capacities in contrast with the remainders, while propanoate revealed an extraordinary capacity when combined with ethyl-based cations. Eventually, the predicted results from COSMO-RS were validated through the experimentally calculated extraction yield of alpha-linolenic acid (ALA) compound from Nannochloropsis sp. microalgae. Three selected ILs namely [EMIM][Cl], [TMAm][Cl], and [EMPyrro][Br] were selected from COSMO-RS for empirical extraction purpose and the validation results pinpointed the good prediction capability of COSMO-RS.


Assuntos
Líquidos Iônicos/química , Microalgas/química , Ácido alfa-Linoleico/química , Ânions/química , Cátions/química , Química Computacional , Íons/química , Modelos Moleculares , Estrutura Molecular , Temperatura , Termodinâmica
9.
J Agric Food Chem ; 68(6): 1654-1665, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31935099

RESUMO

Microalgae accumulate bioavailable selenium-containing amino acids (Se-AAs), and these are useful as a food supplement. While this accumulation has been studied in phototrophic algal cultures, little data exists for heterotrophic cultures. We have determined the Se-AAs content, selenium/sulfur (Se/S) substitution rates, and overall Se accumulation balance in photo- and heterotrophic Chlorella cultures. Laboratory trials revealed that heterotrophic cultures tolerate Se doses ∼8-fold higher compared to phototrophic cultures, resulting in a ∼2-3-fold higher Se-AAs content. In large-scale experiments, both cultivation regimes provided comparable Se-AAs content. Outdoor phototrophic cultures accumulated up to 400 µg g-1 of total Se-AAs and exhibited a high level of Se/S substitution (5-10%) with 30-60% organic/total Se embedded in the biomass. A slightly higher content of Se-AAs and ratio of Se/S substitution was obtained for a heterotrophic culture in pilot-scale fermentors. The data presented here shows that heterotrophic Chlorella cultures provide an alternative for Se-enriched biomass production and provides information on Se-AAs content and speciation in different cultivation regimes.


Assuntos
Aminoácidos/metabolismo , Chlorella/metabolismo , Chlorella/efeitos da radiação , Selênio/metabolismo , Aminoácidos/análise , Biomassa , Chlorella/classificação , Chlorella/crescimento & desenvolvimento , Processos Heterotróficos , Microalgas/química , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Microalgas/efeitos da radiação , Processos Fototróficos , Selênio/análise
10.
BMC Bioinformatics ; 21(1): 1, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31898485

RESUMO

BACKGROUND: The green microalga Dunaliella salina accumulates a high proportion of ß-carotene during abiotic stress conditions. To better understand the intracellular flux distribution leading to carotenoid accumulation, this work aimed at reconstructing a carbon core metabolic network for D. salina CCAP 19/18 based on the recently published nuclear genome and its validation with experimental observations and literature data. RESULTS: The reconstruction resulted in a network model with 221 reactions and 212 metabolites within three compartments: cytosol, chloroplast and mitochondrion. The network was implemented in the MATLAB toolbox CellNetAnalyzer and checked for feasibility. Furthermore, a flux balance analysis was carried out for different light and nutrient uptake rates. The comparison of the experimental knowledge with the model prediction revealed that the results of the stoichiometric network analysis are plausible and in good agreement with the observed behavior. Accordingly, our model provides an excellent tool for investigating the carbon core metabolism of D. salina. CONCLUSIONS: The reconstructed metabolic network of D. salina presented in this work is able to predict the biological behavior under light and nutrient stress and will lead to an improved process understanding for the optimized production of high-value products in microalgae.


Assuntos
Carbono/metabolismo , Clorófitas/metabolismo , Microalgas/metabolismo , Carbono/química , Carotenoides/química , Carotenoides/metabolismo , Clorófitas/química , Clorófitas/efeitos da radiação , Cloroplastos/química , Cloroplastos/metabolismo , Citosol/química , Citosol/metabolismo , Luz , Redes e Vias Metabólicas , Microalgas/química , Microalgas/efeitos da radiação , Mitocôndrias/química , Mitocôndrias/metabolismo , Modelos Biológicos , Estresse Fisiológico
11.
J Biosci Bioeng ; 129(6): 687-692, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31937470

RESUMO

Production of biofuels and fine chemicals from biomass-derived carbohydrates through biorefinery attracts much attention because it is recognized as an environmentally friendly process. Microalgae can serve as promising carbohydrate producers for biorefinery rather than woody and crop biomass due to high biomass productivity, high CO2 fixation, and no competition with food production. However, microalgae with high carbohydrate productivity have not been well investigated despite intensive studies of microalgal lipid production. In this study, the carbohydrate production of Pseudoneochloris sp. strain NKY372003 isolated as a high carbohydrate producer, was investigated. Cultivation conditions with various combinations of nutrient contents and photon flux density were examined to maximize the biomass and carbohydrate productivities. At the optimal condition, the biomass and carbohydrate production of this strain reached 8.11 ± 0.37 g/L and 5.5 ± 0.2 g/L, respectively. As far as we know, this is the highest carbohydrate production by microalgae among ever reported. Cell staining with Lugol's solution visualized intracellular starch granules. Because algal starch can be converted to biofuels and building blocks of fine chemicals, Pseudoneochloris sp. NKY372003 will be a promising candidate for production of fermentable carbohydrates towards biofuels and fine chemicals production.


Assuntos
Clorófitas/metabolismo , Biocombustíveis , Biomassa , Metabolismo dos Carboidratos , Carboidratos/química , Lipídeos/biossíntese , Microalgas/química
12.
Mar Drugs ; 18(1)2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31935955

RESUMO

Osmoregulation in phytoplankton is attributed to several highly polar low-molecular-weight metabolites. A widely accepted model considers dimethylsulfoniopropionate (DMSP) as the most important and abundant osmotically active metabolite. Using an optimized procedure for the extraction and detection of highly polar metabolites, we expand the group of phytoplankton osmolytes by identifying ectoine in several microalgae. Ectoine is known as a bacterial compatible solute, but, to the best of our knowledge, was never considered as a phytoplankton-derived product. Given the ability of microalgae to take up zwitterions, such as DMSP, we tested the hypothesis that the algal ectoine is derived from associated bacteria. We therefore analyzed methanol extracts of xenic and axenic cultures of two different species of microalgae and could detect elevated concentrations of ectoine in those that harbor associated bacteria. However, also microalgae without an associated microbiome contain ectoine in smaller amounts, pointing towards a dual origin of this metabolite in the algae from their own biosynthesis as well as from uptake. We also tested the role of ectoine in the osmoadaptation of microalgae. In the model diatoms Thalassiosira weissflogii and Phaeodactylum tricornutum, elevated amounts of ectoine were found when cultivated in seawater with salinities of 50 PSU compared to the standard culture conditions of 35 PSU. Therefore, we add ectoine to the family of osmoadaptive metabolites in phytoplankton and prove a new, potentially synergistic metabolic interplay of bacteria and algae.


Assuntos
Diamino Aminoácidos/metabolismo , Bactérias/metabolismo , Diatomáceas/metabolismo , Microalgas/metabolismo , Diamino Aminoácidos/isolamento & purificação , Bactérias/química , Diatomáceas/química , Microalgas/química , Salinidade
13.
Arch Insect Biochem Physiol ; 104(1): e21658, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31976574

RESUMO

Managed honey bee colony losses are attributed to a number of interacting stressors, but many lines of evidence point to malnutrition as a primary factor. Commercial beekeepers have become increasingly reliant on artificial pollen substitute diets to nourish colonies during periods of forage scarcity and to bolster colony size before pollination services. These artificial diets may be deficient in essential macronutrients (proteins, lipids, prebiotic fibers), micronutrients (vitamins, minerals), and antioxidants. Therefore, improving the efficacy of pollen substitutes can be considered vital to modern beekeeping. Microalgae are prolific sources of plant-based nutrition with many species exhibiting biochemical profiles that are comparable to natural pollen. This emerging feed source has been employed in a variety of organisms, including limited applications in honey bees. Herein, I introduce the nutritional value and functional properties of microalgae, extrapolating to central aspects of honey bee physiology and health. To conclude, I discuss the potential of microalgae-based feeds to sustainably provision managed colonies on an agricultural scale.


Assuntos
Criação de Abelhas/métodos , Abelhas/fisiologia , Microalgas/química , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Dieta
14.
Molecules ; 25(2)2020 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-31936538

RESUMO

Microalgae are freshwater and marine unicellular photosynthetic organisms that utilize sunlight to produce biomass. Due to fast microalgal growth rate and their unique biochemical profiles and potential applications in food and renewable energy industries, the interest in microalgal research is rapidly increasing. Biochemical and genetic engineering have been considered to improve microalgal biomass production but these manipulations also limited microalgal growth. The aim of the study was the biochemical characterization of recently identified microalgal strain Planktochlorella nurekis with elevated cell size and DNA levels compared to wild type strain that was achieved by a safe non-vector approach, namely co-treatment with colchicine and cytochalasin B (CC). A slight increase in growth rate was observed in twelve clones of CC-treated cells. For biochemical profiling, several parameters were considered, namely the content of proteins, amino acids, lipids, fatty acids, ß-glucans, chlorophylls, carotenoids, B vitamins and ash. CC-treated cells were characterized by elevated levels of lipids compared to unmodified cells. Moreover, the ratio of carotenoids to chlorophyll a and total antioxidant capacity were slightly increased in CC-treated cells. We suggest that Planktochlorella nurekis with modified DNA levels and improved lipid content can be considered to be used as a dietary supplement and biofuel feedstock.


Assuntos
Biomassa , DNA/química , Lipídeos/genética , Microalgas/genética , Biocombustíveis , Clorofila A/biossíntese , Clorofila A/química , DNA/genética , Lipídeos/biossíntese , Lipídeos/química , Microalgas/química , Microalgas/metabolismo , Fotossíntese/genética
15.
Bioengineered ; 11(1): 116-129, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-31909681

RESUMO

The richness of high-value bio-compounds derived from microalgae has made microalgae a promising and sustainable source of useful product. The present work starts with a review on the usage of open pond and photobioreactor in culturing various microalgae strains, followed by an in-depth evaluation on the common harvesting techniques used to collect microalgae from culture medium. The harvesting methods discussed include filtration, centrifugation, flocculation, and flotation. Additionally, the advanced extraction technologies using ionic liquids as extractive solvents applied to extract high-value bio-compounds such as lipids, carbohydrates, proteins, and other bioactive compounds from microalgae biomass are summarized and discussed. However, more work needs to be done to fully utilize the potential of microalgae biomass for the application in large-scale production of biofuels, food additives, and nutritive supplements.


Assuntos
Microalgas/química , Microalgas/crescimento & desenvolvimento , Extratos Vegetais/isolamento & purificação , Biocombustíveis/análise , Biomassa , Meios de Cultura , Líquidos Iônicos/química , Microalgas/metabolismo , Extratos Vegetais/química
16.
Bioengineered ; 11(1): 141-153, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-31994978

RESUMO

Cell immobilization on the magnetic nanoparticles (MNPs) and magnetic harvesting is a novel approach for microalgal cells separation. To date, the effect of these nanoparticles on microalgal cells was only studied over a short period of time. More studies are hence needed for a better understanding of the magnetic harvesting proposes or environmental concerns relating to long-term exposure to nanoparticles. In this study, the impact of various concentrations of MNPs on the microalgal cells growth and their metabolic status was investigated over 12 days. More than 60% reduction in mitochondrial activity and pigments (chlorophyll a, chlorophyll b, and carotenoids) content occurred during the first 6 days of exposure to ≥50 µg/mL nanoparticles. However, more than 50% growth inhibitory effect was seen at concentrations higher than 400 µg/mL. Exposure to MNPs gradually induced cellular adaptation and after about 6 days of exposure to stress generating concentrations (˂400 µg/mL) of IONs, microalgae could overcome the imposed damages. This work provides a better understanding regarding the environmental impact of MNPs and appropriate concentrations of these particles for future algal cells magnetic immobilization and harvesting.


Assuntos
Chlorella vulgaris/química , Nanopartículas/química , Células Imobilizadas/química , Células Imobilizadas/metabolismo , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Clorofila/análise , Clorofila/metabolismo , Clorofila A/análise , Clorofila A/metabolismo , Fenômenos Magnéticos , Microalgas/química , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo
17.
J Biosci Bioeng ; 129(1): 93-98, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31331795

RESUMO

The present study investigated the effect of light intensity and mixing on microalgae growth in a raceway by comparing the performance of a paddlewheel to a combination of paddlewheel and CO2 spargers in a 20 L raceway. The increase of light intensity was known to be able to increase the microalgal growth rate. Increasing paddlewheel rotation speed from 13 to 30 rpm enhanced C. vulgaris growth by enhancing culture mixing. Simulation results using computational fluid dynamics (CFD) indicated that both the turnaround areas of the raceway and the area opposite the paddlewheel experienced very low flow velocities (dead zones) of less than 0.1 m/min, which could cause cell settling and slow down growth. The simulated CFD velocity distribution in the raceway was validated by actual velocity measurements. The installation of CO2 spargers in the dead zones greatly increased flow velocity. The increase of paddlewheel rotation speed reduced the dead zones and hence increased algal biomass production. By complementing the raceway paddlewheel with spargers providing CO2 at 30 mL/min, we achieved a dry cell weight of 5.2 ± 0.2 g/L, which was about 2.6 times that obtained without CO2 sparging.


Assuntos
Dióxido de Carbono/metabolismo , Chlorella vulgaris/metabolismo , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Biomassa , Reatores Biológicos , Dióxido de Carbono/química , Chlorella vulgaris/química , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/efeitos da radiação , Hidrodinâmica , Luz , Microalgas/química , Microalgas/efeitos da radiação
18.
J Biosci Bioeng ; 129(1): 86-92, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31302007

RESUMO

The unicellular green microalga Haematococcus pluvialis accumulates large amounts of the red ketocarotenoid astaxanthin. Aiming to cultivate these microalgae with high astaxanthin efficiency, cultivations were scaled-up from 1000 mL bottle to 2 L and 8 L airlift photobioreactor using volumetric power consumption rate (W/m3) as scale up strategy. After cultivations, computational fluid dynamics (CFD) simulation was used to investigate the flow patterns, mixing efficiency and gas holdup profile within the 2 L photobioreactor. At the end, astaxanthin content was enhanced with increasing the cultivation volume and highest astaxanthin amount of 49.39 ± 1.64 mg/g cell was obtained in 8 L photobioreactor. Hydrodynamic characteristics of photobioreactor was simulated and gas holdup showed difference between the riser and the downcomer regions. Velocity profiles of air and medium had higher values inside the draft tube than obtained in downcomer region. However liquid circulation was achieved from draft tube to the downcomer, mixing was not provided effectively considering the turbulence kinetic energy. For the further research, some developments about column configuration, sparger diameter may be necessary to enhance the mixing characteristics.


Assuntos
Clorófitas/metabolismo , Microalgas/metabolismo , Fotobiorreatores , Clorófitas/química , Clorófitas/crescimento & desenvolvimento , Clorófitas/efeitos da radiação , Hidrodinâmica , Cinética , Luz , Microalgas/química , Microalgas/crescimento & desenvolvimento , Microalgas/efeitos da radiação , Xantofilas/química , Xantofilas/metabolismo
19.
Physiol Plant ; 168(3): 617-629, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31264713

RESUMO

Methods of chlorophyll fluorescence measurements are widely used in the research on photosynthesis and ecophysiology of plants and algae. Among them, a very popular technique is pulse-amplitude-modulation (PAM) flourometry, which is simple to carry out, fast and non-invasive. However, this method is also prone to generate artifacts if the experiments were not planned and executed properly. Application of this technique to algae brings additional complications, which need to be taken into consideration. Some of them are connected with sample preparation and setting of the protocols used, while another origin from the differences in the photosynthetic apparatus and regulation of photosynthesis in various algal groups when compared to vascular plants. In the present paper, some important practical aspects concerning PAM fluorometry measurements in the green microalga Chlamydomonas reinhardtii have been described, including the equipment settings and sample preparation. The impact of growth conditions, such as light, temperature and medium type on the induction of non-photochemical quenching of chlorophyll fluorescence have been also tackled, as well as the question of state transitions occurring in darkness.


Assuntos
Chlamydomonas reinhardtii/química , Clorofila/química , Fluorescência , Fotossíntese , Luz , Microalgas/química
20.
Phytochemistry ; 170: 112200, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31756679

RESUMO

Desmids (Zygnematophyceae) are a group of poorly studied green microalgae. The aim of the present study was to identify fatty acids (FAs) that could be used as biomarkers in desmids in general, and to determine FAs as traits within different ecophysiological desmid groups. FA profiles of 29 desmid strains were determined and analysed with respect to their geographic origin, trophic preference and age of cultivation. It appeared that merely FAs present in relatively large proportions such as palmitic, linoleic, α-linolenic and hexadecatrienoic acids could be used as biomarkers for reliable categorization of this microalgal group. Linear discriminant analysis applied to three a priori defined groups of desmids, revealed clear strain-specific characteristics regarding FA distribution, influenced by climate and trophic conditions at the source sites as well as by the age of culture and growth phase. Accordingly, when considering FAs for the determination of lower taxonomic ranks we recommend using the term "trait" instead of "biomarker", as the latter designates unchangeable "fingerprint" of a specific taxon. Furthermore, despite that desmids were regarded as microalgae having stable genomes, long-term cultivation appeared to cause modifications in FA metabolic pathways, evident as a larger proportion of stearidonic acid in desmid strains cultivated over extensive time periods (>35 years).


Assuntos
Ácidos Graxos/análise , Microalgas/química , Análise Discriminante
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