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- Exploring Pavlova pinguis and Hemiselmis cf. andersenii as natural sources of high-value lipidsPublication . Fernandes, Tomásia Micaela Gomez; Cordeiro, Nereida Maria AbanoA crescente demanda dos consumidores por fontes naturais e sustentáveis de compostos de valor acrescentado tem levado as comunidades científica e industrial a explorar a biodiversidade das microalgas e a sua diversidade química. Na bioprospecção de microalgas para a produção integrada de biomassa e compostos de valor acrescentado, diversos desafios são encontrados, como o cultivo de novas espécies, a identificação de novas moléculas e a otimização das condições de cultivo para a produção dos fitoquímicos desejados. Este estudo investiga o potencial de duas microalgas inexploradas, Hemiselmis cf. andersenii e Pavlova pinguis, como fontes de lípidos com valor acrescentado para aplicação na indústria nutracêutica e áreas relacionadas. A análise dos extratos lipídicos revelou uma grande diversidade de metabolitos sintetizados pela H. cf. andersenii e pela P. pinguis, nomeadamente ácidos gordos, esteróis, álcoois e monoglicerídeos. H. cf. andersenii demonstrou ser rica em ómega-3 polinsaturados. Enquanto, a P. pinguis revelou ser uma grande produtora de fitoesteróis. Para verificar a robustez das microalgas e induzir a acumulação dos compostos desejados, foram realizados estudos com diferente suplementação de azoto e de fósforo no meio de crescimento das microalgas. As condições repletas de azoto revelaram-se eficazes para modelar a composição lipídica das microalgas para as indústrias nutracêutica e farmacêutica. Aumentos dos teores de fósforo induziram um aumento da produtividade da biomassa e da produção de lípidos nutricionalmente relevantes. Na P. pinguis, baixos teores de fósforo mostraram-se eficazes para a produção de carotenoides e açúcares. A H. cf. andersenii mostrou-se promissora para a coprodução de carotenoides e lípidos. A análise multivariada permitiu visualizar os efeitos intra e interespecíficos dos nutrientes na composição lipídica das microalgas. A grande versatilidade de compostos de valor acrescentado produzidos pelas microalgas estudadas aliadas às suas características biológicas (ausência de parede celular rígida), fazem destas candidatas promissoras para futura produção à escala industrial.
- Hemiselmis andersenii and Chlorella stigmatophora as new sources of high‐value compounds: a lipidomic approachPublication . Fernandes, Tomásia; Cordeiro, NereidaTo unlock the potential of Chlorella stigmatophora (Trebouxiophyceae, Chlorophyta) and Hemiselmis andersenii (Cryptophyceae, Cryptophyta) as natural reactors for biotechnological exploitation, their lipophilic extracts were characterized using Fourier Transform Infrared spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and Gas Chromatography-Mass Spectrometry (GC-MS) before and after alkaline hydrolysis. The GC-MS analysis enabled the identification of 62 metabolites-namely fatty acids (27), aliphatic alcohols (17), monoglycerides (7), sterols (4), and other compounds (7). After alkaline hydrolysis, monounsaturated fatty acids increased by as much as 87%, suggesting that the esterified compounds were mainly neutral lipids. Hemiselmis andersenii yielded the highest Σω3/Σω6 ratio (7.26), indicating that it is a good source of ω3 fatty acids, in comparison to C. stigmatophora (Σω3/Σω6 = 1.24). Both microalgae presented significant amounts of aliphatic alcohols (6.81-10.95 mg · g dw-1 ), which are recognized by their cholesterol-lowering properties. The multivariate analysis allowed visualization of the chemical divergence among H. andersenii lipophilic extracts before and after alkaline hydrolysis, as well as species-specific differences. Chlorella stigmatophora showed to be a valuable source of essential fatty acids for nutraceuticals, whereas H. andersenii, due to its high chemical diversity, seems to be suitable for different fields 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.