Browsing by Author "Cunha, Pedro"
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- Effects of outdoor and indoor cultivation on the polar lipid composition and antioxidant activity of Nannochloropsis oceanica and Nannochloropsis limnetica: A lipidomics perspectivePublication . Couto, Daniela; Conde, Tiago A.; Melo, Tânia; Neves, Bruna; Costa, Margarida; Cunha, Pedro; Guerra, Inês; Correia, Nádia; Silva, Joana T.; Pereira, Hugo; Varela, João; Silva, Joana; Domingues, Rosário; Domingues, PedroNannochloropsis is a genus of eicosapentaenoic acid-rich microalgae with high levels of value-added polar lipids. However, the polar lipid composition of microalgal biomass is highly dependent on culture conditions (e.g., light or temperature), which are significantly different under indoor and outdoor culture conditions. In this study, we sought to investigate the plasticity of the polar lipid profile of a marine (N. oceanica) and a freshwater (N. limnetica) species of Nannochloropsis grown in indoor and outdoor photobioreactors. To this end, the polar lipidome and fatty acid profiles were characterized by liquid chromatography-mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS), respectively. In addition, the antioxidant activity of their lipid extracts was assessed. The highest lipid contents were obtained for the two species grown indoors. LC-MS analysis identified 239 different polar lipid species, of which 220 were shared by all experimental groups. Candidate lipid biomarkers from both culture systems were proposed, including MGDG(34:2), MGDG(34:1) and PG(36:6). For both species, indoor conditions lead to lipid extracts rich in glycolipids and higher in oleic acid content. In contrast, outdoor conditions lead to higher proportions of phospholipids and betaine lipids and a higher relative content of eicosapentaenoic acid (EPA). The polar lipid profile of the two Nannochloropsis species differed primarily in the relative amounts of certain betaine lipids, mainly DGTS (which was increased in N. oceanica) and lysolipids (LPC, and LPE) (increased in N. limnetica), although the majority of lipids were observed in both species. The lipid extracts showed antioxidant activity (IC15) ranging from 30.4 +/- 1.8 to 45.7 +/- 1.6 mu mol Trolox g-1 of lipid extract. Overall, this study provides insight into the lipid metabolic adaptation of two Nannochloropsis species, providing the know-how to obtain a healthy polar lipid-rich biomass useful for novel applications in pharmaceutical, nutraceutical, or novel foods.
- Nannochloropsis oceanica cultivation in pilot-scale raceway ponds—from design to cultivationPublication . Cunha, Pedro; Pereira, Hugo; Costa, Margarida; Pereira, João; Silva, Joana T.; Fernandes, Nuno; Varela, João; Silva, Joana; Simões, ManuelRaceways ponds are the microalgal production systems most commonly used at industrial scale. In this work, two di erent raceway configurations were tested under the same processing conditions to compare their performance on the production of Nannochloropsis oceanica. Biomass productivity, biochemical composition of the produced biomass, and power requirements to operate those reactors were evaluated. Water depths of 0.20 and 0.13 m, and culture circulation velocities of 0.30 and 0.15 m s1 were tested. A standard configuration, which had a full channel width paddlewheel, proved to be the most energy e cient, consuming less than half of the energy required by a modified configuration (had a half channel width paddlewheel). The later showed to have slightly higher productivity, not enough to o set the large di erence in energetic consumption. Higher flow velocity (0.30 m s1) led to a 1.7 g m2 d1 improvement of biomass productivity of the system, but it increased the energy consumption twice as compared to the 0.15 m s1 flow velocity. The latter velocity showed to be the most productive in lipids. A water depth of 0.20 m was the most suitable option tested to cultivate microalgae, since it allowed a 54% energy saving. Therefore, a standard raceway pond using a flow velocity of 0.3 m s1 with a 0.20 m water depth was the most e cient system for microalgal cultivation. Conversely, a flow velocity of 0.15 m s1 was the most suitable to produce lipids.
- The lowermost Tejo River terrace at Foz do Enxarrique, Portugal: a palaeoenvironmental archive from c. 60–35 ka and its implications for the Last Neanderthals in Westernmost IberiaPublication . Cunha, Pedro; Martins, António; Buylaert, Jan-Pieter; Murray, Andrew; Gouveia, Maria; Font, Eric; Pereira, Telmo; Figueiredo, Silvério; Ferreira, Cristiana; Bridgland, David; Yang, Pu; Stevaux, José; Mota, RuiReconstruction of Pleistocene environments and processes in the sensitive geographical location of westernmost Iberia, facing the North Atlantic Ocean, is crucial for understanding impacts on early human communities. We provide a characterization of the lowest terrace (T6) of the Lower Tejo River, at Vila Velha de Rodao (eastern central Portugal). This terrace comprises a lower gravel bed and an upper division consisting of fine to very fine sands and coarse silts. We have used a multidisciplinary approach, combining geomorphology, optically stimulated luminescence (OSL) dating, grain-size analysis and rock magnetism measurement, in order to provide new insights into the environmental changes coincident with the activity of the last Neanderthals in this region. In addition, we conducted palynological analysis, X-ray diffraction measurement and scanning electron microscopy coupled with energy dispersive spectra of the clay fraction and carbonate concretions. We discuss these new findings in the context of previously published palaeontological and archeological data. The widespread occurrence of carbonate concretions and rizoliths in the T6 profile is evidence for episodic pedogenic evaporation, in agreement with the rare occurrence and poor preservation of phytoliths. We provide updated OSL ages for the lower two Tejo terraces, obtained by post infra-red stimulated luminescence: (i) T5 is c. 140 to 70 ka; (ii) T6 is c. 60 to 35 ka. The single archaeological and fossiliferous level located at the base of the T6 upper division, recording the last regional occurrence of megafauna (elephant and rhinoceros) and Mousterian artefacts, is now dated at 44 +/- 3 ka. With reference to the arrival of Neanderthals in the region, probably by way of the Tejo valley (from central Iberia), new dating suggests a probable age of 200-170 ka for the earliest Mousterian industry located in the topmost deposits of T4.