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‣ Contributos para o desenvolvimento de um Biosensor no cultivo de microalgas

Silva, Cátia
Fonte: Instituto Politécnico de Leiria Publicador: Instituto Politécnico de Leiria
Tipo: Dissertação de Mestrado
Publicado em 15/12/2011 Português
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Dissertação de Mestrado em Biotecnologia dos Recursos Marinhos apresentada à ESTM - Escola Superior de Turismo e Tecnologia do Mar do Instituto Politécnico de Leiria; O cultivo de Isochrysis galbana e de Nannochloropsis gaditana foi efetuado em diferentes tipos de fotobioreactores (PBR). Para tal, foram definidas as curvas de crescimento para cada microalga e PBR, através da contagem direta das células por hematócitometro. De seguida estabeleceram-se as diferentes fases de crescimento para cada cultivo. Paralelamente à contagem direta das células foi efetuado por espectrofotómetria um varrimento dos 400nm aos 700nm, no qual se obtiveram os seguintes comprimentos de onda 422nm, 441nm, 540nm e 547nm. Os comprimentos de onda obtidos foram correlacionados com a densidade celular, permitindo através da análise estatística definir uma reta-padrão para cada tipo de reator e microalga. A reta-padrão da I. galbana foi definida a 441nm no balão volumétrico e no PBR airlift. Por outro lado a reta-padrão da N. gaditana foi definida a 540nm, nos mesmos PBR. O PBR coluna de bolhas não permitiu a definição de uma reta-padrão devido à reduzida fase exponencial presente em ambos os cultivos. Ao longo do tempo estimou-se a clorofila a...

‣ Search for mycosporine-like amino acids and fatty acids in Isochrysis galbana and Nannochloropsis gaditana

Furtado, Joana
Fonte: Instituto Politécnico de Leiria Publicador: Instituto Politécnico de Leiria
Tipo: Dissertação de Mestrado
Publicado em //2011 Português
Relevância na Pesquisa
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Dissertação de Mestrado em Biotecnologia dos Recursos Marinhos apresentada à ESTM - Escola Superior de Turismo e Tecnologia do Mar do Instituto Politécnico de Leiria; In this work two unialgal cultures, one of Isochrysis galbana (I. galbana) and another of Nannochloropsis gaditana (N. gaditana), were exposed to photosynthetic active radiation (PAR) plus ultraviolet radiation (UVR-B) (supplemented with 4h daily) in a photoperiod 16h: 8h, light: dark cycle. The content on mycosporine-like amino acids (MAAs) was determined by reverse phase isocratic high performance liquid chromatography (HPLC) employing C18 phase, in methanolic and aqueous methanolic extracts. No MAAs were identified, with the five standards available, but a peak (unknown compound) with absorption maximum (ëmax) at 338 nm was detected. The content on fatty acids (only for N. gaditana) was determined by gas chromatography (GC), eight fatty acids were identified (in ten presented in N. gaditana) and the most abundant fatty acid was the palmitic acid with 26,86% of the total fatty acids. In order to identify new sources of safe and inexpensive antioxidants, the antioxidant activity of different fractions of N. gaditana was evaluated, by the á,á-diphenyl-â-picrylhydrazyl (DPPH) radical scavenging assay. The N. gaditana was extracted using nhexane...

‣ Influência de duas dietas (náuplios de Artemia e Artemia enriquecida) no crescimento e sobrevivência de larvas de Lavagante, Homarus gammarus

Pereira, Paulo David
Fonte: Instituto Politécnico de Leiria Publicador: Instituto Politécnico de Leiria
Tipo: Dissertação de Mestrado
Publicado em 14/12/2011 Português
Relevância na Pesquisa
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Dissertação de Mestrado em Aquacultura apresentada à ESTM - Escola Superior de Turismo e Tecnologia do Mar do Instituto Politécnico de Leiria; Nas últimas décadas, verificou-se a instalação em alguns países europeus de maternidades de Lavagante Europeu, Homarus gammarus, com o objectivo de produzir juvenis para repovoamento em zonas em que o stock natural sofreu uma acentuada depleção. No entanto, a definição de dietas bem ajustadas às larvas de Homarus gammarus e as taxas de sobrevivência relativamente baixas devido a canibalismo constituem desafios e continuam a originar estudos nesta matéria. Neste trabalho foram testadas duas dietas, naúplios de Artemia salina e Artemia salina enriquecida durante 24h com a microalga Isochrysis galbana, com o objectivo de avaliar a sua influência no crescimento e na sobrevivência larvar. Para o cultivo recorreu-se a um sistema de recirculação de água, em tanques de fundo cónico de 4 l. O trabalho foi iniciado com uma densidade de cultivo de 5 larvas/l e mantido a uma temperatura de 23-24ºC, uma salinidade de 33 ‰ e com um fotoperíodo de 12h Luz: 12h Escuro. Nas condições de realização deste estudo, que foi desenvolvido até ao dia 10 pós eclosão, não se observaram diferenças estatisticamente significativas nas mortalidades das larvas entre as duas dietas. No entanto...

‣ Functional biscuits with PUFA-omega 3 from Isochrysis galbana

Gouveia, Luísa; Coutinho, Carla; Mendonça, Emanuel; Batista, Ana Paula; Sousa, Isabel; Bandarra, Narcisa; Raymundo, Anabela
Fonte: Society of Chemical Industry Publicador: Society of Chemical Industry
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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BACKGROUND: Sweet biscuits, a traditional and nutritious food, can be healthy and very attractive when redesigned to be prepared with the addition of a natural product, themicroalgal biomass of Isochrysis galbana.This marine microalga is recognised as a rich source of polyunsaturated fatty acids (PUFAs), mainly eicosapentaenoic acid (EPA; 20:5ω3), and is a promising ingredient in the food and feed industries. The importance of PUFA-ω3 (an alternative to fish oils) in food, and the need to increase the daily intake of these substances to promote a healthier lifestyle is now well known. RESULTS: Traditional butter biscuits were enriched with I. galbana biomass (1% and 3%) and evaluated in terms of colour, texture and fatty acid profile, within 3months of storage. I. galbana biscuits presented total levels of 100mg 100 g−1 and 320mg 100 g−1 of PUFA-ω3 (EPA + DPA (docosapentaenoic acid; 22:5ω3) + DHA (docosahexaenoic acid; 22:6ω3) for 1% and 3% I. galbana, respectively. CONCLUSION: The enhancement of texture properties, the high stability of colour and texture and the good profile of polyunsaturated fatty acids, with emphasis on EPA and DHA, of the biscuits obtained, reveal a new food market niche opportunity.

‣ Isochrysis galbana and Diacronema vlkianum biomass incorporation in pasta products as PUFA’s source

Fradique, Mónica; Batista, Ana Paula; Nunes, Cristiana M.; Gouveia, L.; Bandarra, Narcisa M.; Raymundo, Anabela
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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Factors such as an ageing population, increased health care costs and rapid advances in science and technology are likely driving the increase interest among consumers in attaining wellness through diet, which is in turn, fuelling interest in functional foods and changing the way that people eat. Microalgae have been largely cultured and commercialized as food and feed additives, their potential as source of high-added value compounds and their ability to positively affect human’s health due to their original chemical composition, is well known. Considering pasta is a main staple food, the objective of this study was to prepare fresh spaghetti enriched with different amounts of microalgae and to compare the fatty acid profile of pastas before and after cooking, with standard semolina spaghetti. The results show that fatty acid profile of pastas prepared with Isochrysis galbana and Diacronema vlkianum biomass incorporation, presented a high resistance to the thermal treatment applied during the cooking procedure. The increase of the amount of the algae lead to a significant increase of EPA (Eicosapentaenoic Acid) and DHA (Docosahexaenoic Acid) both in raw and cooked pastas, omega-3 fatty acids that can be obtained through seafood.

‣ Compostos bioactivos de microalgas com interesse em aquacultura como imunoestimulantes, antioxidantes e antibióticos

Mendes, Nuno Gonçalo Ramos
Fonte: Universidade do Algarve Publicador: Universidade do Algarve
Tipo: Dissertação de Mestrado
Publicado em //2011 Português
Relevância na Pesquisa
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Dissertação de mest., Aquacultura e Pescas (Aquacultura), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011; As microalgas têm um papel fundamental na produção de diversos organismos marinhos, principalmente na sua fase larvar, sendo indispensáveis à sua criação. Para além da sua importância nutricional, diversos estudos apontam para a existência de outros compostos com propriedades imunomodulatórias em microalgas. Estes compostos podem ajudar a reduzir os impactos nos surtos de zoonoses em instalações de aquacultura, nomeadamente na de Sparus aurata. Neste trabalho estudou-se a actividade biológica de extractos aquosos das microalgas Tetraselmis chuii (T-iso), Isochrysis galbana, Nannochloropsis oculata, Scenedesmus sp. e Botryococcus braunii em relação à sua influência no respiratory burst de fagócitos de Sparus aurata e à capacidade antimicrobiana sobre Listonella anguillarum, Vibrio fischeri e Photobacterium danselae piscicida dos extractos aquosos, de hexano acetona e éter dietílico das referidas microalgas. Também se determinou a actividade antioxidante dos extractos aquosos por método de DPPH e por capacidade quelante de Fe2+ e Cu2+. O presente trabalho apontou para a existência de propriedades antioxidantes...

‣ Expression of the Isochrysis C18-Δ9 Polyunsaturated Fatty Acid Specific Elongase Component Alters Arabidopsis Glycerolipid Profiles1

Fraser, Thomas Colin Michael; Qi, Baoxiu; Elhussein, Salah; Chatrattanakunchai, Sunantha; Stobart, Allan Keith; Lazarus, Colin Michael
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /06/2004 Português
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A cDNA isolated from the prymnesiophyte micro-alga Isochrysis galbana, designated IgASE1, encodes a fatty acid elongating component that is specific for linoleic acid (C18:2n-6) and α-linolenic acid (C18:3n-3). Constitutive expression of IgASE1 in Arabidopsis resulted in the accumulation of eicosadienoic acid (EDA; C20:2n-6) and eicosatrienoic acid (ETrA; C20:3n-3) in all tissues examined, with no visible effects on plant morphology. Positional analysis of the various lipid classes indicated that these novel fatty acids were largely excluded from the sn-2 position of chloroplast galactolipids and seed triacylglycerol, whereas they were enriched in the same position in phosphatidylcholine. EDA and ETrA are precursors of arachidonic acid (C20:4n-6), eicosapentaenoic acid (C20:5n-3), and docosahexaenoic acid (C22:6n-3) synthesized via the so-called ω6 Δ8 desaturase and ω3 Δ8 desaturase biosynthetic pathways, respectively. The synthesis of significant quantities of EDA and ETrA in a higher plant is therefore a key step in the production of very long chain polyunsaturated fatty acid in oil-seed species. The results are further discussed in terms of prokaryotic and eukaryotic pathways of lipid synthesis in plants.

‣ Effects of Variations in Daylength and Temperature on Net Rates of Photosynthesis, Dark Respiration, and Excretion by Isochrysis galbana Parke 1

Hobson, Louis A.; Hartley, F. Alexandra; Ketcham, Dawn E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1979 Português
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The effects of variable daylength and temperature on net rates of photosynthesis, dark respiration, and excretion of a unicellular marine haptophyte, Isochrysis galbana Parke, were examined and related to division rates. Six combinations of daylength (18:6, 12:12, 6:18 light:dark, LD) and temperature (20, 25 C) were used. Daily rates of net photosynthesis were closely correlated to division rates, suggesting a direct relationship, and were maximal when cells were grown at 12:12 LD at both temperatures and 18:6 LD at 20 C. A daylength of 6 hours decreased daily rates by decreasing the time for carbon uptake. Further, cells grown with this daylength had maximal chlorophyll a contents, suggesting a physiological adaptation by photosynthetic units to short light periods. A photoperiod of 18:6 LD at 25 C decreased daily rates of net photosynthesis by reducing the hourly rate of net photosynthesis via an unidentified mechanism. The importance of rates of net dark respiration in controlling daily net photosynthesis was small, with carbon lost during dark periods varying between 4 and 14% of that gained during light periods. Also, the influence of net excretion was small, varying between 1.0 and 5.5% of daily net photosynthesis.

‣ Proteomic Analysis in Nitrogen-Deprived Isochrysis galbana during Lipid Accumulation

Song, Pingping; Li, Ling; Liu, Jianguo
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 05/12/2013 Português
Relevância na Pesquisa
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The differentially co-expressed proteins in N-deprived and N-enriched I. galbana were comparatively analyzed by using two dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight-mass spectrometry (MALDI-TOF/TOF-MS) with the aim of better understanding lipid metabolism in this oleaginous microalga. Forty-five of the 900 protein spots showed dramatic changes in N-deprived I. galbana compared with the N-enriched cells. Of these, 36 protein spots were analyzed and 27 proteins were successfully identified. The identified proteins were classified into seven groups by their molecular functions, including the proteins related to energy production and transformation, substance metabolism, signal transduction, molecular chaperone, transcription and translation, immune defense and cytoskeleton. These altered proteins slowed cell growth and photosynthesis of I. galbana directly or indirectly, but at the same time increased lipid accumulation. Eight key enzymes involved in lipid metabolism via different pathways were identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycerate kinase (PGK), enolase, aspartate aminotransferase (AST), fumarate hydratase (FH), citrate synthase (CS)...

‣ Cultivation of Isochrysis galbana in Phototrophic, Heterotrophic, and Mixotrophic Conditions

Alkhamis, Yousef; Qin, Jian G.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Português
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This study compared the growth and biomass production of Isochrysis galbana under hetero-, mixo-, and phototrophic conditions using different organic carbon sources. The growth of I. galbana was inhibited in heterotrophy but was enhanced in mixotrophy compared to that in phototrophy. Subsequently, the influences of organic carbon and environmental factors (light and salinity) on the growth of I. galbana were further investigated. Algal dry weight increased as glycerol concentrations increased from 0 to 200 mmol and the highest algal production occurred at 50 mmol glycerol. At a range of light intensities of 25–200 μmol photons m−2 s−2, the highest algal growth rate occurred at 100 photons μmol m−2 s−2. The growth of I. galbana was significantly affected by photoperiod, and the maximal dry weight was obtained at 12 h light and 12 h dark. In the salinity test, I. galbana could grow in a wide range of salinities from 10 to 65‰, but the 35‰  salinity was optimal. This study suggests that the growth and production of I. galbana can be improved using mixotrophic culture at 50 mmol glycerol in 35‰  salinity.

‣ Influência do estresse nutricional programado na composição da microalga isochrysis galbana

Chagas, Bruna Maria Emerenciano das
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Química; Pesquisa e Desenvolvimento de Tecnologias Regionais Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Química; Pesquisa e Desenvolvimento de Tecnologias Regionais
Tipo: Dissertação Formato: application/pdf
Português
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Global warming due to Greenhouse Gases (GHG) emissions, especially CO2, has been identified as one of the major problems of the twenty-first century, considering the consequences that could represent to planet. Currently, biological processes have been mentioned as a possible solution, especially CO2 biofixation due to association microalgae growth. This strategy has been emphasized as in addition to CO2 mitigation, occurs the production of biomass rich in compounds of high added value. The Microalgae show high photosynthetic capacity and growth rate higher than the superior plants, doubling its biomass in one day. Its culture does not show seasons, they grow in salt water and do not require irrigation, herbicides or pesticides. The lipid content of these microorganisms, depending on the species, may range from 10 to 70% of its dry weight, reaching 90% under certain culture conditions. Studies indicate that the most effective method to promote increased production of lipids in microalgae is to induce stress by limiting nitrogen content in the culture medium. These evidences justify research continuing the production of biofuels from microalgae. In this paper, it was studied the strategy of increasing the production of lipids in microalgae I. galbana with programmed nutritional stress...

‣ Avaliação da produção de biodiesel de microalga Isochrysis galbana via transesterificação in situ; Evaluation of biodiesel production from microalgae Isochrysis galbana via in situ transesterification

Procópio, Zaniel Souto Dantas
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Química; Pesquisa e Desenvolvimento de Tecnologias Regionais Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Química; Pesquisa e Desenvolvimento de Tecnologias Regionais
Tipo: Dissertação Formato: application/pdf
Português
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Microalgae are microscopic photosynthetic organisms that grow rapidly and in different environmental conditions due to their simple cellular structure. The cultivation of microalgae is a biological system capable of storing solar energy through the production of organic compounds via photosynthesis, and these species presents growth faster than land plants, enabling higher biomass yield. Thus, it is understood that the cultivation of these photosynthetic mechanisms is part of a relevant proposal, since, when compared to other oil producing raw materials, they have a significantly higher productivity, thus being a raw material able to complete the current demand by biodiesel . The overall aim of the thesis was to obtain biofuel via transesterification process of bio oil from the microalgae Isochrysis galbana. The specific objective was to estimate the use of a photobioreactor at the laboratory level, for the experiments of microalgae growth; evaluating the characteristics of biodiesel from microalgae produced by in situ transesterification process; studying a new route for disinfection of microalgae cultivation, through the use of the chemical agent sodium hypochlorite. The introduction of this new method allowed obtaining the kinetics of the photobioreactor for cultivation...

‣ Effects of nitrogen source and growth phase on proximate biochemical composition, lipid classes and fatty acid profile of the marine microalga "Isochrysis Galbana"

Fidalgo Paredes, Pablo; Cid Blanco, Ángeles; Torres, Enrique; Sukenik, A.; Herrero López, Concepción
Fonte: Universidade da Corunha Publicador: Universidade da Corunha
Tipo: Artigo de Revista Científica
Português
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[Abstract]The marine microalga Isochrysis galbana was cultured in nitrate, nitrite or urea media to examine changes in the gross biochemical composition, with special emphasis on the growth phase associated changes in the compositions of the lipid classes and fatty acids. The gross biochemical composition was affected more by the growth phase than by the nitrogen source. Protein was higher during exponential growth (about 37–45% AFDW) but the pattern changed as the cultures aged, and lipids were the main algal constituents on all nitrogen sources in the late stationary phase. In all cultures, the relative abundance of neutral lipid increased in the late stationary phase concomitant with a proportional reduction in phospholipids, whereas galactolipids only slightly changed during the growth of the cultures. Total fatty acid content was affected by nitrogen source and growth phase. Maximal PUFA values were obtained at the early stationary phase and decreased throughout the stationary phase. The highest fatty acid contents in the early stationary phase were produced in urea cultures; these cultures also had higher PUFA content, with EPA and DHA contents of 27.66% and 14.13% of total fatty acids, respectively.

‣ Marine microalgae as a potential source of single cell protein (SCP)

Fábregas, Jaime; Herrero López, Concepción
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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The marine microalgae Tetraselmis suecica, Isochrysis galbana, Dunaliella tertiolecta and Chlorella stigmatophora are good biological sources of single cell protein (SCP). Protein content accounts for 39.12%–54.20% of the dry matter, D. tertiolecta having the highest. Lysine values are between 3.67 and 4.52 g/100 g of protein, and thus are higher than those for freshwater species. The total nucleic acid content is less than 7% of the dry matter; this value is definitely lower than that for yeasts or bacteria, commonly used as SCP sources. Amino acid profiles of the four species are very similar and comparable to the FAO reference protein, buth with a low content of methionine and cystine and a high content of lysine. The MEAA indices are between 81 and 84.98, without significant differences among the four species. Marine microalgae can be used as a potential SCP source.

‣ Yields in biomass and chemical constituents of four commercially important marine microalgae with different culture media

Herrero López, Concepción; Cid Blanco, Ángeles; Fábregas, Jaime; Abalde Alonso, Julio Ernesto
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
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The use of the commercial nutrient Algal-1 was studied in mass cultures of the marine microalgaeTetraselmis suecica, Dunaliella tertiolecta, Isochrysis galbana and Phaeodactylum tricornutum, in comparison with the use of media such as ES-Provasoli, and Walne medium. Maximum cell concentrations were always found in Algal-1 cultures and these values were always significantly higher than those obtained in the remaining media. The cellular density obtained in Algal-1 cultures was between 59% and 79% higher than that obtained in the traditional culture media used for T. suecica, between 70% and 109% for D. tertiolecta, between 33% and 60% for I. galbana and between 63% and 105% for P. tricornutum. The culture medium used affected the chemical composition of microalgal cells. Protein is the major cellular component for all the sepcies assayed and with all the media proved. Maximum values of protein/cell were obtained in Algal-1 cultures, except for P. tricornutum, whereas maximum values of reserve products (carbohydrates and lipids) never occurred in Algal-1 cultures, except for T. suecica. Differences in the protein content were higher than those found in the other cellular constituents. Maximum values of protein, lipids and carbohydrates per liter of culture always occurred in Algal-1 cultures...

‣ Marine microalgae as a potential source of minerals in fish diets

Fábregas, Jaime; Herrero López, Concepción
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
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The incorporation of powdered marine microalgae in fish diets can substitute, at least in part, for the addition of minerals to the diet. In diets for freshwater fishes, the incorporation of 33% of powdered marine microalgae can supply some of the mineral element requirements. The incorporation of microalgal powder in diets for marine fishes appears more effective, since lower percentages are needed to cover the mineral requirements. Most mineral needs of turbot can be covered with low percentages of marine microalgal powder in the diet: 3.8% of Tetraselmis suecica, 5.7% of Isochrysis galbana, 3.57% of Dunaliella tertiolecta and 3.9% of Chlorella stigmatophora. Mn and Co must, however, be added. Thus, incorporation of small amounts of marine microalgae in diets can replace a mineral mixture.

‣ Nutritional properties of four marine microalgae for albino rats

Herrero López, Concepción; Abalde Alonso, Julio Ernesto; Fábregas, Jaime
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Português
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The nutritive value of the marine microalgaeTetraselmis suecica, Isochrysis galbana, Dunaliella tertiolecta and Chlorella stigmatophora was studied in diets given to rats. Biological assays were carried out in order to determine the Protein Efficiency Ratio (PER) and the Food Conversion Efficiency (FCE). Each dried microalga was fed to weaning Wistar albino rats as the sole protein source at a protein level of 12%. Control rats were given diets containing 12 % casein. Food consumption was similar in all groups. PER values obtained were 1.14 with T. suecica diet, 1.13 with I. galbana diet, 2.07 with D. tertiolecta diet and 1.13 with C. stigmatophora diet (casein, 2.50). FCE values followed a similar pattern. The data showed that the marine microalga D. tertiolecta is a source of protein of good quality. Its PER is quite high, compared to vegetable and cereal proteins, and compares favourably with other microbial protein sources, such as yeasts or different freshwater microalgae. Haematological tests showed no significant differences among the groups in haemoglobin levels, red and white blood cell counts, differential count and mean corpuscular volume. Different blood parameters were also determined and a significant decrease in triglycerides levels appeared with all the microalgal diets...

‣ Growth, chlorophyll α and protein of the marine microalga Isochrysis galbana in batch cultures with different salinities and high nutrient concentrations

Fábregas, Jaime; Herrero, Concepción; Abalde Alonso, Julio Ernesto; Cabezas, Buenaventura
Fonte: Elsevier Science Publishers Publicador: Elsevier Science Publishers
Tipo: info:eu-repo/semantics/acceptedVersion
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Cultures of the marine microalga Isochrysis galbana were grown under 56 different nutrient concentration-salinity conditions, ranging from 1 to 64 mM NaNO3 and from 0 to 35‰ salinity. Salinity and nutrient concentration were found to be closely related to I. galbana growth and to the biochemical composition. Optimal growth conditions were between 15 and 35‰ salinity and nutrient concentrations of 2, 4 and 8 mM NaNO3, resulting in one doubling/day and a maximum cellular density of 20 × 106cells/ml. Variations in salinity and in nutrient concentration had a greater effect on the final biomass than on the growth velocity. Maximum values of chlorophyll α ml were found with 2, 4 and 8 mM NaNO3 and between 15 and 35‰ salinity. Chlorophyll α cell values were more homogeneously distributed between 15 and 35‰ salinity and 1 to 8 mM NaNO3, although maximum concentrations (37 pg chlorophyll α cell) were reached at 10-15‰ with all the nutrient concentrations. Protein per ml of culture and protein per cell were closely related to salinity and nutrient concentration. Maximum values of 387 μg/ml and 18.6 pg/cell were obtained at 15-35‰ salinity and 4-8 mM NaNO3. The nitrate-protein transformation rate was related to nutrient concentration. Maximum rate was 84% at 15‰ salinity and 1 mM NaNO3. Nutrient concentrations higher than 16 mM NaNO3 produced a strong decrease in the efficiency at all salinities.

‣ Biomass production and biochemical composition in mass cultures of the marine microalga Isochrysis galbana Parke at varying nutrient concentrations

Fábregas, Jaime; Herrero, Concepción; Cabezas, Buenaventura; Abalde Alonso, Julio Ernesto
Fonte: Elsevier Science Publishers Publicador: Elsevier Science Publishers
Tipo: info:eu-repo/semantics/acceptedVersion
Português
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Mass cultures of Isochrysis galbana were carried out with four nutrient concentrations ranging from 2 to 16 mM of NaNO3 and salinity 35‰. An air flow of 15 l/min maintained a CO2 transference rate sufficient to keep the pH below 8.4. Using these conditions, equations were calculated by a multiple non-linear least squares regression of order four, enabling predictions to be made of growth kinetics and chemical composition. Maximum cellular density of 65.5 × 106 cells/ml was obtained with 4 mM NaNO3. Cellular volume was constant in the different nutrient concentrations. Protein content reached a maximum value of 374 μg/ml at 4 mM of NaNO3, and this concentration also presented the maximum efficiency of transformation from nitrate to protein, i.e. 114%. As a result, lowest costs for harvesting are obtained at a nutrient concentration of 4 mM NaNO3. Efficiencies decreased to 15% as nutrient concentration increased. Maximum values of chlorophyll a (21.9 μg/ml) and carbohydrates (213 μg/ml) were also obtained with 4 mM NaNO3. In the logarithmic phase, the contents of protein, chlorophyll a, carbohydrates, RNA and DNA per cell were constant. Chlorophyll a reached values between 0.15 and 0.33 pg/cell in the stationary phase. Carbohydrate levels reached the maximum value of 3.16 pg/cell with 4 mM NaNO3 in the stationary phase. The levels of RNA/cell and DNA/cell were constant in all the nutrient concentrations tested and in both growth phases...

‣ Comparison of microalgal biomass profiles as novel functional ingredient for food products

Batista, Ana Paula; Gouveia, L.; Bandarra, Narcisa M.; Franco, J. M.; Raymundo, Anabela
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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Microalgae are one of the most promising sources for new food and functional food products, and can be used to enhance the nutritional value of foods, due to their well-balanced chemical composition. Knowing their physicochemical characteristics is fundamental for the selection of the most suitable microalgae to specific food technology applications and consequently successful novel foods development. The aim of this study is to screen the chemical composition (e.g., proteins, pigments, fatty acids) and thermogravimetry properties of five microalgae species with potential application in the food industry: Chlorella vulgaris (green and carotenogenic), Haematococcus pluvialis (carotenogenic), Spirulina maxima, Diacronema vlkianum and Isochrysis galbana. C. green and S. maxima presented high protein (38% and 44%, respectively), low fat content (5% and 4%, respectively). The carotenogenic C. vulgaris and H. pluvialis showed a higher carotenoid content, higher fat, low protein and better resistance to thermal treatment. D. vlkianum and I. galbana presented high protein (38–40%) and fat (18–24%) contents with PUFA's?3, mainly EPA and DHA. Finally, the results from microalgae chemical and thermal analysis were grouped and correlated through Principal Components Analysis (PCA) in order to determine which variables better define and differentiate them.