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- Nutritional value and fatty acid profile of two wild edible limpets from the Madeira ArchipelagoPublication . Fernandes, Igor; Fernandes, Tomásia; Cordeiro, NereidaPatella aspera and Patella candei are two abundant limpet species commercially exploited and often used as a delicacy in the Madeira Archipelago, but there is a lack of scientific knowledge about these species. This study investigated the nutritional value and fatty acids of this species across the coast of Madeira Archipelago. The lipid content (7.71–12.60% dw), proteins (48.22–64.09% dw), ashes (11.12–23.12% dw) and carbohydrates (4.5–10.9% dw) were determined in P. aspera and P. candei at different collection sites. In the fatty acid composition, a total of 23 fatty acids (FAs) were identified. P. aspera showed the highest amount of monounsaturated FAs (MUFAs, 35.02%) and eicosapentaenoic acid (EPA, 12.59%), and P. candei presented the highest level of oleic acid (OA, 28.25%), polyunsaturated FAs (PUFAs, 27.26%) and arachidonic acid (AA, 11.38%). The Σω3/Σω6 dietary ratio presented levels>0.25 suggesting that these marine molluscs are a good source of ω3 for dietary intake. Within each specie significant differences (p<0.05) across sites were observed. High amounts of essential nutrients were shown in Patella species collected at Selvagens site while poorest levels were shown in Patella collected at Lido. The evaluation of the nutritional traits of P. candei and P. aspera shows that these limpets are good sources of essential fatty acids for human health and that the distribution of limpets is a key factor when determining its dietary value.
- Lipid and fatty acid composition of wild Almaco Jack Seriola rivoliana at two maturation stagesPublication . Fernandes, Igor; Nogueira, Natacha; Faria, Graça; Fernandes, Tomásia; Faria, Marisa; Cordeiro, NereidaAlmaco jack (Seriola rivoliana) is an emergent marine finfish that presents high market value. In order to study the feasibility of the exploitation of this marine resource for human consumption the evaluation of the nutritional characteristics of this species has attracted the attention of the scientific community. The lipid characteristics and fatty acid composition were evaluated in muscle, liver and gonad tissues of wild Almaco jack from Atlantic Ocean at two different maturation stages. According to results, the lipid content was found higher at pre-spawning stage (21.78 - 36.17%) and highest proportion being exhibited in the liver. Palmitic acid was predominant among the saturated fatty acids (35.42 - 47.80%) and oleic acid was detected as the main monounsaturated acid (25.26 - 36.55%). Higher amounts of ω3 polyunsaturated fatty acids (PUFAs) were identified in gonads of resting females, of which more than 84% was accounted by docosahexaenoic acid (12.62%). Muscle and liver of resting females presented the highest ω3/ω6 ratios. The Hypocholesterolemic/Hypercholesterolemic index was higher in gonads of both maturation stages (0.97 and 1.05). The results showed that wild Almaco jack at resting stage were a better source of oleic acid and ω3 PUFAs and that liver and gonads present good nutritional by-products.
- Marine microalgae monosaccharide fluctuations as a stress response to nutrients inputsPublication . Fernandes, Tomásia; Fernandes, Igor; Andrade, Carlos A. P.; Ferreira, Artur; Cordeiro, NereidaThe monosaccharide patterns of the microalgae species Nannochloropsis gaditana, Rhodomonas marina and Isochrysis sp. were assessed, to verify if nutrients availability had an impact on these parameters. Isochrysis sp. and Rhodomonas marina monosaccharides content decreased 13–94% as the nutrients availability increased. The relative abundance of monosaccharides depicted that, at low nutrients availabilities, Rhodomonas marina and Isochrysis sp. had preference for glucans synthesis, accounting for up to 75% of the monosaccharides detected. Linking the monosaccharides trends with the phylogeny and glycolipid data, it was possible to establish which monosaccharides had a structural and/or storage role in the microalgae studied. Thermal analysis revealed that the microalgae submitted to low nutrient input treatments presented a reduced assimilation of the inorganic compounds. Nutrient concentrations affected microalgae monosaccharide patterns, highlighting their taxonomic differences.
- Changes in fatty acid biosynthesis in marine microalgae as a response to medium nutrient availabilityPublication . Fernandes, Tomásia; Fernandes, Igor; Andrade, Carlos A. P.; Cordeiro, NereidaTo maximize and enhance the fatty acid (FA) profiles of microalgae, it is crucial to understand the metabolic path ways that lead to high levels of the desired product. Nannochloropsis gaditana, Rhodomonas marina, and Isochrysis sp. were cultivated in media with various nutrient concentrations, and the biomass was analyzed for protein and fatty acid contents. The long chain polyunsaturated fatty acid (LC-PUFA) and protein contents were maximized in media with high nutrient concentrations. Under these conditions, the reduction in the (SFA + MUFA)/PUFA ratio (by as much as 83%) indicated that R. marina and N. gaditana shifted preference towards PUFA synthesis. The ∑ω3/∑ω6 ratio indicated that R. marina preferentially synthesized ω3 FA towards high nutrient concentrations (depicted by an eightfold increase) in contrast to Isochrysis sp. (which yielded a 35% reduction). In addition, the limitations of LC-PUFA biosynthesis at the level of its precursors (e.g. C18:2ω6, C18:3ω3, C18:4ω3) and further conversion to LC-PUFA as nutrients were increased, suggesting that external variations induced changes in the sets of enzymes that maintain the desaturation and elongation pathways of FA. The present study provides novel insights into the regulation of LC-PUFA biosynthesis and facilitates the modeling of microalgal FA patterns depending on the field of application.
- Marine microalgae growth and carbon partitioning as a function of nutrient availabilityPublication . Fernandes, Tomásia; Fernandes, Igor; Andrade, Carlos A. P.; Cordeiro, NereidaTo understand in which way the structural differences of three marine microalgae (Nannochloropsis gaditana, Rhodomonas marina and Isochrysis sp.) affect their carbon partitioning, growth and applicability; a stoichiometric imbalance was imposed by steady carbon and other nutrients variation. Towards high nutrients concentrations/low carbon availability a decrease of 12-51% in C/N microalgae ratio was observed and maximum cell densities were achieved. Moreover, linear correlation between the nutrient input and microalgae protein content were observed. The macromolecular ratios pointed that carbohydrate was the main contributor for the C/N decrement. Although lipid content in R. marina remained constant throughout the experiment, a rise of 37-107% in N. gaditana and Isochrysis sp. was verified. Lipid fractions revealed high percentages of glycolipids in all microalgae (57-73% of total lipids). The present study shows an easy way to understand and modulate microalgae carbon partitioning relying on the field of application.
- Enrichment of bioactive compounds in microalgae for aquaculturePublication . Fernandes, Tomásia Micaela Gomez; Cordeiro, Nereida Maria Abano; Andrade, Carlos Alberto PestanaMicroalgae are promising microorganisms for the production of food and fine chemicals. Several species of microalgae are used in aquaculture with the purpose of transfer bioactive compounds up to the aquatic food chain. The main objective of this project was to develop a stress–inducement strategy in order to enhance the biochemical productivity of Nannochloropsis gaditana, Rhodomonas marina and Isochrysis sp. for aquaculture purposes having in account their growth and organizational differences. In this regard, two experiments were design: the first one consisted on the alteration of overall nutrient availabilities in growth medium; and the second one comprised changes in nitrogen and sulfur concentrations maintaining the concentrations of the other nutrients present in a commercial growth medium (Nutribloom plus), which is frequently used in aquaculture. Microalgae dried biomass was characterized biochemically and elemental analysis was also performed for all samples. In first experimental design: linear trends between nutrient availability in growth media and microalgae protein content were obtained; optimum productivities of eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) were attained for both R. marina and N. gaditana in growth media enriched with 1000 L L-1 of nutrient solution whereas for Isochrysis sp. the double of Nutribloom plus was needed; the decrease of glucans and total monosaccharides with nutrient availability for R. marina and Isochrysis sp. showed the occurrence of a possible depletion of carbohydrates towards lipids and proteins biosynthesis. Second experimental desing: N. gaditana exhibited the highest variation in their biochemical composition against the applied perturbation; variations observed for microalgae in their biochemical composition were reflected in their elemental stoichiometry; in N. gaditana the highest nitrogen concentrations lead to overall maximum productivities of the biochemical parameters. The results of the present work show two stress-inducement strategies for microalgae that may constitute a base for further investigations on their biochemical enhancement.
- A comparative analysis of lipid content and fatty acid composition in muscle, liver and gonads of Seriola fasciata Bloch 1793 based on gender and maturation stagePublication . Nogueira, Natacha; Fernandes, Igor; Fernandes, Tomásia; Cordeiro, NereidaThe fat content and fatty acid profile of commercially important Seriola fasciata (Lesser amberjack) was determined in samples of muscle, liver and gonads of both genders at pre-spawning and spawning stage. Results indicated that edible muscle of pre-spawning fish had high fat content(>8%), lowering to medium fat (4–8%) content during spawning stage. Livers and gonads presented more constant and relatively high lipid contents. Saturated fatty acids constituted the majority of the fatty acids, followed by monounsaturated fatty acids, with palmitic acid and oleic acid as the major fatty acid in all tissues. EPA and DHA content increased in spawning females and highest amounts were observed in the ovaries (222 and 1440 mg/100 g respectively). Livers presented lowest PUFAs content regardless of maturity stage and Sn 6/Sn 3 ratio was influenced by gender in this organ. Sn 3/Sn 6 was gender related during pre-spawning stage, increasing in spawning maturation stage. Results highlight variations in the nutritional value of the different tissues according to maturity stage and gender, emphasizing the need for consumer awareness of these changes.