Browsing by Author "Raposo, Sara"
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- Alternative chemo-enzymatic hydrolysis strategy applied to different microalgae species for bioethanol productionPublication . Constantino, Ana; Rodrigues, Brígida; Leon, R.; Barros, Raúl; Raposo, SaraMicroalgae have been considered third generation feedstock for biofuel production based on the expectation that large amounts of algal biomass can be cultivated at an acceptable cost. Transformation of biomass into ethanol requires a saccharification step, where complex carbohydrates are broken down by hydrolysis into sugars that can be fermented to bioethanol. Carbohydrate mobilization is hampered by the recalcitrance of the cell envelope of microalgal cells, because complex structural polysaccharides are difficult to depolymerize and make internal carbohydrate reserves inaccessible to hydrolysis. Saccharification can be accomplished by either acidic hydrolysis, enzymatic treatment or a combination of both. The present work focused on the chemo-enzymatic hydrolysis of lyophilized biomass of different microalgae and subsequent fermentation of hydrolysates with higher reducing sugar content. A chemo-enzymatic hydrolysis strategy was defined, consisting of an acid pretreatment carried out at high pressure and temperature, followed by incubation with Amyloglucosidase and finally by incubation with alpha-Amylase, the opposite order of the conventional use of these enzymes. An increase of reducing sugar yield of about one third was observed, and this strategy was successfully applied to a broad group of microalgae, resulting in maximum release yields of at least 34.0 +/- 1.0 g total reducing sugar/100 g dry biomass. For bioethanol production studies, the microalgae hydrolysates of Chlorella sorokiniana, Tetraselmis sp. (Necton) and Skeletonema sp. were selected according to their high reducing sugar content. High ethanol production was achieved with all hydrolysates, with ethanol yields close to the theoretical maximum and the highest ethanol concentrations so far reported under comparable conditions. Chlorella sorokiniana stood out as the best hydrolysate for ethanol production, with an ethanol yield of 0.464 +/- 0.013 g/g reducing sugar and ethanol productivity of 0.344 +/- 0.020 g/L.h.
- Antioxidant activity and enzyme inhibitory potential of Euphorbia resinifera and E. officinarum honeys from Morocco and plant aqueous extractsPublication . Boutoub, Oumaima; EL-Geundouz, Soukaina; Estevinho, Leticia M.; Paula, Vanessa B.; Aazza, Smail; El Ghadraoui, Lahsen; Rodrigues, Brígida; Raposo, Sara; Carlier, Jorge; Costa, Maria Clara; Miguel, MariaNatural products may be applied in a wide range of domains, from agriculture to food and pharmaceutical industries. In this study, the antioxidant properties and the capacity to inhibit some enzymatic activities ofEuphorbia resiniferaandEuphorbia officinarumaqueous extracts and honeys were assessed. The physicochemical characteristics were also evaluated. Higher amounts of iron, copper and aluminium were detected inE. officinarumhoney, which may indicate environmental pollution around the beehives or inadequate storage of honey samples. This honey sample showed higher amounts of total phenols and better capacity for scavenging superoxide anion free radicals and DPPH free radicals as compared withE. resiniferahoney, but poorer capacity for inhibiting lipoxygenase, acetylcholinesterase, tyrosinase and xanthine oxidase. The ratio plant mass:solvent volume (1:100) and extraction time (1 - 2 h) were associated with higher total phenols and better antioxidant activities and lipoxygenase, acetylcholinesterase and tyrosinase inhibitory activities, regardless of the plant species. The aqueous extracts had systematically higher in vitro activities than the respective honey samples.
- Antioxidant activity of thyme waste extract in O/W emulsionsPublication . EL-GEUNDOUZ, Soukaina; AAZZA, Smail; Anahi Dandlen, Susana; MAJDOUB, Nesrine; Lyoussi, Badiaa; Raposo, Sara; Antunes, Maria Dulce; Gomes, Vera; Miguel, MariaThymus vulgaris (thyme) is an aromatic plant and its essential oil has been applied as antimicrobial and antioxidant due to the presence of phenolic compounds. However, after steam distillation, the deodorized plant material is rejected, despite the possible presence of bioactive compounds. Ethanolic thyme waste extract revealed the presence of benzoic acid, 4-hydroxybenzoic acid, ferulic acid, caffeic acid, and sinapic acid. This waste thyme extract had the capacity for preventing the formation of primary and secondary lipid oxidation products in emulsions O/W (oil in water), constituted by diverse proportions of wheat and almond oils, without interfering with the viscosity parameters, for 10 weeks, at 37 °C. The increasing proportion of almond oil (≥50%) in the emulsion increases its resistance to oxidation, which is improved with the presence of an optimal concentration of tested thyme waste extract (0.02% and 0.04%). The waste thyme extract can, therefore, be used as an antioxidant either in food or pharmaceutical emulsions O/W, replacing the synthetic antioxidants.
- Application of the focused beam reflectance measurement method (FBRM) to the characterization of plant cells in suspension culturePublication . Jeffers, Paul; Raposo, Sara; Lima-Costa, Maria Emília; Kieran, Patricia; Glennon, BrianThe ability to determine biomass levels and organism morphological characteristics is of importance in many bioprocesses.
- Are native microalgae consortia able to remove microplastics from wastewater effluents?Publication . Afonso, Valdemira; Borges, Rodrigo; Rodrigues, Brígida; Barros, Raúl; Bebianno, Maria; Raposo, SaraWastewater Treatment Plants (WWTPs) are potential sources of microplastics (MPs) in the aquatic environment. This study aimed to investigate the potential of wastewater-native microalgae consortia to remove MPs from the effluent of two different types of WWTPs as a dual-purpose solution for MPs mitigation and biomass production. For that purpose, the occurrence of MPs from two types of WWTP effluents was analysed over one year. MPs were characterized in terms of morphology (microbead, foam, granule, irregular, filament and film), colour and size. The wastewater characterisation was followed by the removal of MP loads, using native microalgae consortia, pre-adapted to the wastewater effluent. Microalgae consortia evolved naturally through four mitigation assays, adapted to seasonal conditions, such as temperature, photoperiod, and wastewater composition. MPs were present in all the effluent samples, ranging from 52 to 233 MP L− 1 . The characterisation of MPs indicated a predominance of white and transparent particles, with irregular and filament shapes, mainly under 500 μm in size. The μFTIR analysis revealed that 43% of the selected particles were plastic, with a prevalence of poly propylene (PP) (34%) and polyethylene terephthalate (PET) (30 %). In the mitigation experiments, substantial biomass production was achieved (maximum of 2.6 g L− 1 (d.w.)), with successful removal of MPs, ranging from 31 ± 25% to 82 ± 13%. These results show that microalgae growth in wastewater effluents efficiently promotes the removal of MPs, reducing this source of contamination in the aquatic environment, while generating valuable biomass. Additionally, the strategy employed, requires minimal control of culture conditions, simplifying the integration of these systems in real-world WWTP facilities for improved wastewater management.
- Biochemical characterization of the amylase activity from the New Haloarchaeal Strain Haloarcula sp. HS isolated in the Odiel MarshlandsPublication . Gómez-Villegas, Patricia; Vigara, Javier; Romero, Luis; Gotor, Cecilia; Raposo, Sara; Gonçalves, Brígida; Léon, RosaAlpha-amylases are a large family of α,1-4-endo-glycosyl hydrolases distributed in all kingdoms of life. The need for poly-extremotolerant amylases encouraged their search in extreme environments, where archaea become ideal candidates to provide new enzymes that are able to work in the harsh conditions demanded in many industrial applications. In this study, a collection of haloarchaea isolated from Odiel saltern ponds in the southwest of Spain was screened for their amylase activity. The strain that exhibited the highest activity was selected and identified as Haloarcula sp. HS. We demonstrated the existence in both, cellular and extracellular extracts of the new strain, of functional α-amylase activities, which showed to be moderately thermotolerant (optimum around 60 ◦C), extremely halotolerant (optimum over 25% NaCl), and calcium-dependent. The tryptic digestion followed by HPLC-MS/MS analysis of the partially purified cellular and extracellular extracts allowed to identify the sequence of three alpha-amylases, which despite sharing a low sequence identity, exhibited high three-dimensional structure homology, conserving the typical domains and most of the key consensus residues of α-amylases. Moreover, we proved the potential of the extracellular α-amylase from Haloarcula sp. HS to treat bakery wastes under high salinity conditions.
- Bioethanol production using carob pod, as carbon source on submerged fermentationPublication . Lima-Costa, Maria Emília; Sousa, Catarina; Rodrigues, B.; Quintas, Célia; Raposo, SaraIn the latest years the research for new sources of carbon sources, among industry by-products as potential raw material for bioethanol production is a needful and a sustainable strategy for the success of 2nd generation biofuels.
- Biofuels production by chlorella sorokiniana in a biorefinery perspectivePublication . Constantino, Ana; Glória, Patrícia; Rodrigues, Brígida; Leon, Rosa; Barros, Raúl; Raposo, SaraBiofuels Production By Chlorella Sorokiniana In A Biorefinery Perspective (Poster Presentation) in Abstract Book 5th Algaeurope Conference
- Biogas production from microalgal biomass produced in the tertiary treatment of urban wastewater: assessment of seasonal variationsPublication . Barros, Raúl; Raposo, Sara; Morais, Etiele; Rodrigues, Brígida; Lourenço Afonso, Valdemira; Gonçalves, Pedro; Marques, José; Cerqueira, Ricardo; Varela, João; Ribau Teixeira, Margarida; Barreira, LuísaThe valorization of microalgal biomass produced during wastewater treatment has the potential to mitigate treatment costs. As contaminated biomass (e.g., with pharmaceuticals, toxic metals, etc.) is often generated, biogas production is considered an effective valorization option. The biomass was obtained from a pilot facility of photobioreactors for tertiary wastewater treatment. The pilots were run for one year with naturally formed microalgal consortia. The biogas was generated in 70 mL crimp-top vials at 35 °C, quantified with a manometer and the methane yield measured by gas chromatography. A maximum biogas production of 311 mL/g volatile solids (VS) with a methane yield of 252 mL/g VS was obtained with the spring samples. These rather low values were not improved using previous thermo-acidic hydrolysis, suggesting that the low intrinsic biodegradable organic matter content of the consortia might be the cause for low yield. Considering the total volume of wastewater treated by this plant and the average amount of methane produced in this study, the substitution of the current tertiary treatment with the one here proposed would reduce the energy consumption of the plant by 20% and create an energy surplus of 2.8%. The implementation of this system would therefore contribute towards meeting the ambitious decarbonization targets established by the EU.
- Biotecnologia Marinha – biocombustíveis, biorrefinaria e alimentos innovadoresPublication . Varela, João; Raposo, Sara; Pereira, Hugo; Barreira, LuísaApesar de fazer parte da estratégia de “blue growth” da União Europeia, a biotecnologia marinha ainda é uma atividade pouco explorada para desenvolver a economia local, nacional e transnacional ligada ao mar. No entanto, esta actividade de investigação tem a capacidade de gerar emprego altamente qualificado e com um potencial de inovação elevado. Através de uma colaboração entre dois grupos de investigação da Universidade do Algarve e companhias como a NECTON e SPAROS, estão-se a dar os primeiros passos para a implementação do conceito de biorrefinaria com vista ao aproveitamento integral e sustentável da biomassa de microalgas marinhas. Esse aproveitamento permitirá a produção de biocombustíveis na forma de biodiesel e bioetanol, a formulação de alimentos, rações e cosméticos inovadores e isolamento de compostos bioactivos com aplicação biomédica de alto valor acrescentado. Além disso, esforços de bioprospeção deram lugar ao isolamento de uma microalga susceptível de ser cultivada em efluentes de ETARs. O objectivo final será aliar a produção de biocombustíveis ao tratamento de águas, possibilitando assim uma fonte potencial de rendimento, que poderão aliviar os orçamentos municipais através de uma redução dos custos de operação.