Browsing by Author "Cardoso, Helena"
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- Heterotrophic and photoautotrophic media optimization using response surface methodology for the Novel Microalga Chlorococcum amblystomatisPublication . Correia, Nádia; Pereira, Hugo; Schulze, Peter S.C.; Costa, Monya; Santo, Gonçalo E.; Guerra, Inês; Trovão dos Santos, Mafalda; Barros, Ana; Cardoso, Helena; Silva, Joana L.; Gouveia, Luisa; Varela, JoãoThe nutritional requirements of novel microalgal strains are key for their effective cultivation and metabolite content. Therefore, the optimization of heterotrophic and photoautotrophic culture media is crucial for novel Chlorococcum amblystomatis growth. Heterotrophic and photoautotrophic biomass samples were characterized to identify the differences between their heterotrophic and photoautotrophic biomass composition and their biotechnological potential. Media optimization through surface response methodology led to 44.9 and 51.2% increments in C. amblystomatis-specific growth rates under heterotrophic and photoautotrophic growth, respectively. This microalga registered high protein content (61.49–73.45% dry weight), with the highest value being observed in the optimized photoautotrophic growth medium. The lipid fraction mainly constituted polyunsaturated fatty acids, ranging from 44.47 to 51.41% for total fatty acids (TFA) in cells under heterotrophy. However, these contents became significantly higher (70.46–72.82% TFA) in cultures cultivated under photoautotrophy. An interesting carotenoids content was achieved in the cultures grown in optimized photoautotrophic medium: 5.84 mg·g−1 β-carotene, 5.27 mg·g−1 lutein, 3.66 mg·g−1 neoxanthin, and 0.75 mg·g−1 violaxanthin. Therefore, C. amblystomatis demonstrated an interesting growth performance and nutritional profile for food supplements and feed products that might contribute to meeting the world’s nutritional demand.
- Heterotrophic cultivation of Chlorella vulgaris yellow mutant on sidestreams: Medium formulation and process scale-upPublication . Trovão, Mafalda; Barros, Ana; Machado, Adriana; Reis, Ana; Pedroso, Humberto; Espírito Santo, Gonçalo; Correia, Nádia; Costa, Monya; Ferreira, Sara; Varela, João; Cardoso, Helena; Silva, Joana; Pereira, Hugo; Freitas, FilomenaMicroalgal protein is a promising feedstock to complement and/or replace other protein sources. Besides requiring less land and water usage, microalgae production is a more sustainable process, especially if industrial sidestreams are used as nutrient sources. Additionally, the heterotrophic cultivation of microalgae, such as Chlorella vulgaris, enables the achievement of much higher biomass productivity and lower areal footprint than autotrophic cultivation. Chlorophyll-deficient strains of C. vulgaris, as the yellow strain 7Y, provide microalgal biomass with improved sensory properties. In line with this, a waste-based medium was formulated to cultivate this strain, aiming at maximum biomass productivity. In this context, several industrial sidestreams were screened, and two food wastes and corn molasses were selected for their high nitrogen and glucose concentrations, respectively. The waste-based medium formulated was compared to the inorganic optimised medium at laboratory scale in Erlenmeyer flasks and 7-L reactors. The results obtained in the 7-L fermenters revealed that both conditions achieved similar biomass productivities and growth rates of approximately 14 g L-1 d-1 and 0.8 d-1, respectively. The biomass and protein productivities were further enhanced by supplying a higher nitrogen concentration in the feeding solution when the process was scaled-up to 200-L reactors, reaching 22 and 6.3 g L-1 d-1, respectively, thus validating the developed industrial waste-based medium for the efficient cultivation of C. vulgaris under heterotrophic conditions.
- High prevalence of cardiovascular disease and risk factors among type 2 diabetes patients followed in a hospital setting in Portugal: the PICT2RE observational studyPublication . Cardoso, Helena; Bello, Carlos Tavares; Andrade, Luís; Rosário, Francisco Sobral do; Louro, Joana; Nogueira, Cláudia; Rodrigues, Elisabete; Vieira, Nuno Bernardino; Carqueja, TeresaPortugal is a country with a high prevalence of type 2 diabetes (T2D) and cardiovascular disease (CVD). The prevalence of CVD and cardiovascular (CV) risk factors among T2D patients followed in hospitals in Portugal is not known. The primary objective of this study was to assess the prevalence of CVD and CV risk factors among T2D patients in a hospital setting in Portugal. The clinical management of CVD in the hospital setting was also assessed.
- Impact of seasons on industrial cultivation of Limnospira platensis (Spirulina): a year-round case study on biomass, phycocyanin, and protein productivity in PortugalPublication . Guerra, Inês; Torres, Cátia; Cardoso, Helena; Pereira, Hugo; Trovão, Mafalda; Rodrigues, Alexandre M. C.; Varela, JoãoSpirulina is the most commercially produced biomass, among microalgae and cyanobacteria, with extensive applications across food, feed, nutraceutical and biotechnological sectors. While Spirulina cultivation is wellcharacterized at laboratorial and small-scale production, critical knowledge gaps remain regarding industrialscale production in temperate climates. Specifically, there is a lack of robust empirical data on how seasonal environmental fluctuations affect year-round productivity and the maintenance of consistent biomass quality (protein, phycocyanin content) under large-scale operational constraints. This study evaluates the year-round industrial production of Limnospira platensis in large-scale (1000 m2 and 4000 m2 ) raceway reactors at Allmicroalgae - Natural Products S.A., Portugal. Biomass productivity as well as protein and phycocyanin contents across different seasons and throughout the day were assessed. The influence of environmental factors such as temperature and solar radiation on productivity and biomass composition was also analyzed. Industrially grown Spirulina reached an average annual productivity of 5.1–5.6 g.m− 2 .d− 1 . Seasonal variation revealed a winter productivity decline higher than 60 %, compared to peak yields of 7.5–7.6 g.m− 2 .d− 1 from April to September. Protein content remained consistent year-round between 58.4 and 64.7 %, whereas phycocyanin content presented strong solar radiation dependence, peaking at 15.2 % in summer and decreasing to 10.4 % in winter. Furthermore, an analysis throughout the day identified an optimal harvesting window between midday and sunset to maximize phycocyanin levels. These findings validate the industrial feasibility of year-round Spirulina cultivation in temperate climates and provide seasonal productivity forecasting and harvest timing optimization, towards protein consistency and phycocyanin yield optimization.
- Insight into the efficiency of microalgae’ lipidic extracts as photosensitizers for Antimicrobial Photodynamic Therapy against Staphylococcus aureusPublication . Mendonça, Inês; Silva, Daniela; Conde, Tiago; Maurício, Tatiana; Cardoso, Helena; Pereira, Hugo; Bartolomeu, Maria; Vieira, Cátia; Domingues, M. Rosário; Almeida, AdelaideAntibacterial resistance causes around 1.27 million deaths annually around the globe and has been recognized as a top 3 priority health threat. Antimicrobial photodynamic therapy (aPDT) is considered a promising alternative to conventional antibiotic treatments. Algal lipid extracts have shown antibacterial effects when used as photosensitizers (PSs) in aPDT. In this work we assessed the photodynamic efficiency of lipidic extracts of microalgae belonging to different phyla (Bacillariophyta, Chlorophyta, Cyanobacteria, Haptophyta, Ochrophyta and Rhodophyta). All the extracts (at 1 mg mL−1) demonstrated a reduction of Staphylococcus aureus >3 log10 (CFU mL−1), exhibiting bactericidal activity. Bacillariophyta and Haptophyta extracts were the top-performing phyla against S. aureus, achieving a reduction >6 log10 (CFU mL−1) with light doses of 60 J cm−2 (Bacillariophyta) and 90 J cm−2 (Haptophyta). The photodynamic properties of the Bacillariophyta Phaeodactylum tricornutum and the Haptophyta Tisochrysis lutea, the best effective microalgae lipid extracts, were also assessed at lower concentrations (75 μg mL−1, 7.5 μg mL−1, and 3.75 μg mL−1), reaching, in general, inactivation rates higher than those obtained with the widely used PSs, such as Methylene Blue and Chlorine e6, at lower concentration and light dose. The presence of chlorophyll c, which can absorb a greater amount of energy than chlorophylls a and b; rich content of polyunsaturated fatty acids (PUFAs) and fucoxanthin, which can also produce ROS, e.g. singlet oxygen (1O2), when photo-energized; a lack of photoprotective carotenoids such as β-carotene, and low content of tocopherol, were associated with the algal extracts with higher antimicrobial activity against S. aureus. The bactericidal activity exhibited by the extracts seems to result from the photooxidation of microalgae PUFAs by the 1O2 and/or other ROS produced by irradiated chlorophylls/carotenoids, which eventually led to bacterial lipid peroxidation and cell death, but further studies are needed to confirm this hypothesis. These results revealed the potential of an unexplored source of natural photosensitizers (microalgae lipid extracts) that can be used as PSs in aPDT as an alternative to conventional antibiotic treatments, and even to conventional PSs, to combat antibacterial resistance.
- Isolation and selection of protein-rich mutants of chlorella vulgaris by fluorescence-activated cell sorting with enhanced biostimulant activity to germinate garden cress seedsPublication . Trovão dos Santos, Mafalda; Schüler, Lisa; Pedroso, Humberto; Reis, Ana; Santo, Gonçalo Espírito; Barros, Ana; Correia, Nádia; Ribeiro, Joana; Bombo, Gabriel; Gama, Florinda; Viana, Catarina; Costa, Monya; Ferreira, Sara; Cardoso, Helena; Varela, João; Silva, Joana; Freitas, Filomena; Pereira, HugoMicroalgae are a promising feedstock with proven biostimulant activity that is enhanced by their biochemical components (e.g., amino acids and phytohormones), which turns them into an appealing feedstock to reduce the use of fertilisers in agriculture and improve crop productivity and resilience. Thus, this work aimed to isolate protein-rich microalgal mutants with increased biostimulant activity. Random mutagenesis was performed with Chlorella vulgaris, and a selection of protein-rich mutants were sorted through fluorescence-activated cell sorting (FACS), resulting in the isolation of 17 protein-rich mutant strains with protein contents 19-34% higher than that of the wildtype (WT). Furthermore, mutant F4 displayed a 38%, 22% and 62% higher biomass productivity, growth rate and chlorophyll content, respectively. This mutant was then scaled up to a 7 L benchtop reactor to produce biomass and evaluate the biostimulant potential of this novel strain towards garden cress seeds. Compared to water (control), the germination index and the relative total growth increased by 7% and 19%, respectively, after the application of 0.1 g L-1 of this bioproduct, which highlights its biostimulant potential.
- Microalgae as a selenium vehicle for nutrition: a reviewPublication . Pires, Rita; Costa, Margarida; Pereira, Hugo; Cardoso, Helena; Ferreira, Luís; Lapa, Nuno; Silva, Joana; Ventura, MárciaSelenium (Se) is essential for human and animal nutrition, playing a key role in antioxidant and immune functions. Organic Se is better for supplementation because it is more efficiently assimilated and less toxic than its inorganic form. Due to the scarcity of Se in European soils, supplementation in feed and food is necessary. Currently, inorganic Se (sodium selenite and selenate) and organic Se in Se-enriched yeast are approved by the European Food Safety Authority (EFSA) to address Se deficiency. However, Se-enriched microalgae present a promising alternative. By supplementing their growth media with Se, microalgae convert it into organic forms like Se-cysteine and Se-methionine, creating Se-enriched biomass. This biomass can serve as a valuable Se source with the additional benefits of microalgae. This review evaluates the viability of microalgae as a Se supplementation vehicle in food and feed and explores its commercial applications in the European Union (EU), along with emerging projects and innovations in the field.
- Oxyfluorfen: a novel metabolic inhibitor to select microalgal chlorophyll-deficient mutant strains for nutritional applicationsPublication . Trovão dos Santos, Mafalda; Cardoso, Lucas; Schüler, Lisa; Machado, Adriana; Santo, Gonçalo Espírito; Pedroso, Humberto; Reis, Ana; Barros, Ana; Correia, Nádia; Costa, Monya; Ferreira, Sara; Cardoso, Helena; Mateus, Marília; Silva, Joana; Pereira, Hugo; Freitas, Filomena; Varela, JoãoNowadays, there is an increasing demand for novel feedstocks and alternative protein sources to meet global needs. Because of their rich nutritional profiles and high protein contents, microalgae-based food products and supplements are being developed. Nonetheless, these products present organoleptic characteristics such as taste, smell and colour that are often considered unpleasant by human and animal consumers. To address this constraint, strain improvement approaches such as random mutagenesis have been used, which combined with the right selection strategy, lead to more appealing microalgal biomass. In this work, a novel selection strategy using oxyfluorfen, an inhibitor of the chlorophyll synthesis pathway, was applied for the first time to isolate chlorophyll-deficient strains of Scenedesmus rubescens and Chlorella vulgaris upon treatment with ethyl methanesulfonate (EMS). With this approach, one S. rubescens brownish (37Y01) mutant strain, as well as two C. vulgaris mutant strains, one yellow (31Y15) and one white (31W62), were obtained. S. rubescens 37Y01 displayed a reduced protein content of 19.1% dry weight (DW) compared to that of the wildtype, which presented a protein content of 25.0% DW. C. vulgaris wildtype and mutants exhibited higher protein contents, in the 42.844.3% DW range, compared to Scenedesmus rubescens (p < 0.05). The selective pressure of this inhibitor allowed the selection of S. rubescens and C. vulgaris mutants displaying 55% and 95% decrease in chlorophyll content, respectively. The reduced chlorophyll content greatly improves the sensory properties and consumer acceptance of established mutants, increasing the potential of both strains as feedstocks to develop novel food products.