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- Towards sustainable seaweed production: Optimising the culture of Gracilaria gracilisPublication . Ferreira, Francisco; Freitas, Marta; Cavaco, Mário; Mouga, TeresaGracilaria gracilis is a well-known cultivated seaweed, sought after for its high agar content. For this purpose, it is one of the most cultivated species worldwide. Depending on the biotic and abiotic conditions to which it is exposed, the species also exhibits a very interesting nutritional profile, making it an excellent candidate for use as a food or food supplement. Thus, aiming to improve the productivity and biomass quality, G. gracilis was cultivated under different light conditions and nutrient media, to evaluate the impact of these parameters on the growth rate and the chemical composition of the biomass. Thus, the nutritional profile of the biomass was evaluated. Our results indicate that environmental parameters have a significant impact both on growth and quality of the biomass, affecting the amount of protein, ash, and carbohydrate. The cultivation methods, therefore, significantly affected the quality of the biomass produced. Thus, there is scope to optimise the cultivation of G. gracilis, in order to efficiently produce high quality biomass, enhancing the effective use of resources, particularly nutrients, while producing nutritionally balanced biomass for human consumption.
- Seasonal nutritional profile of Gelidium corneum (Rhodophyta, Gelidiaceae) from the center of PortugalPublication . Cavaco, Mário; Duarte, Adriana; Freitas, Marta; Afonso, Clélia; Bernardino, Susana M.; Pereira, Leonel; Martins, Mendelson; Mouga, TeresaGelidium corneum is a well-known agarophyte, harvested worldwide for its high agar quality. However, the species also exhibits an interesting nutritional profile, but with seasonal variations. Therefore, to evaluate the nutritional value of G. corneum, ash, crude protein, total lipids, and carbohydrates were analyzed at different times of the year. The heavy metals mercury, arsenic, lead, cadmium, and tin, as well as iodine were also measured. Finally, the seasonal antioxidant capacity of G. corneum extracts was evaluated. Our results indicate that the biomass is rich in protein (up to 16.25 ± 0.33%) and carbohydrates (up to 39.5 ± 3.29%), and low in lipids (up to 2.75 ± 0.28%), and especially in the summer, the AI, TI indexes, n-6/n-3 and h/H ratios (0.93, 0.6, 0.88 and 1.08, respectively) are very interesting. None of the contaminants exceeded the legally established limits, and the iodine values were adequate for a healthy diet. Finally, the antioxidant capacity is fair, with the DPPH ≤ 10.89 ± 1.46%, and ABTS ≤ 13.90 ± 1.54% inhibition, FRAP ≤ 0.91 ± 0.22 AAE.g−1, and TPC ≤ 6.82 ± 0.26 GAE.g−1. The results show that G. corneum is an attractive resource, with potential use as food or as a food supplement.
- The biotechnological potential of the seaweed Gracilariopsis longissima (Rhodophyta, Gracilariales)Publication . Freitas, Marta Alexandra dos Santos Veríssimo; Mouga, Teresa Margarida Lopes da Silva; Afonso, Clélia Paulete Correia NevesRecentemente, a humanidade tem sondado os oceanos na procura de fontes naturais de compostos bioativos, tais como os provenientes de macroalgas, que hoje em dia ocupam lugares de destaque em campos da Ciência e Medicina. As macroalgas figuram na história e tradição de várias culturas, sendo hoje em dia exploradas e cultivadas para diversos propósitos, dependendo da espécie e país, mas geralmente como alimento ou produção de ficocolóides. A alga Gracilariopsis longissima (Rhodophyta, Gracilariales) pertence a uma família de macroalgas vermelhas amplamente autenticadas pelo seu valor como agarófitas, sendo a espécie em si ultimamente reconhecida em sistemas IMTA como biorremediadora. A alga G. longissima da Lagoa de Óbidos foi assim o objeto do presente estudo, estando este dividido em dois capítulos principais, relativos a pesquisa com objetivos distintos. O Capítulo Um foca-se sobretudo na avaliação das taxas de crescimento de G. longissima em salinidades distintas e sob condições controladas, e onde se inferiu que a macroalga apresenta o melhor crescimento e performance a uma salinidade de 35‰ (com um aumento de comprimento de 1.611%.dia-1, e 16 novas ramificações), não sobrevivendo contudo em salinidades de 15‰ e inferiores. O Capítulo Dois estabelece um perfil nutricional para G. longissima, nomeadamente deteção de sazonalidade no conteúdo em proteína e determinação do perfil lipídico, fornecendo também um parecer sobre variação sazonal na sua atividade antioxidante. Foi igualmente testada sazonalidade na atividade antimicrobiana, contra as bactérias Escherichia coli, Bacillus subtilis e Vibrio alginolyticus. Os resultados indicam um considerável conteúdo em proteína (desde 11.19 a 27.04% de peso seco), e um perfil de ácidos gordos rico em ácido araquidónico e ácido palmítico (36.78 e 43.84 % do total de ácidos gordos, respetivamente) mostrando, no entanto, uma fraca atividade antioxidante (conteúdo total em polifenóis desde 0.54 a 1.90 mg EAG.g-1, e atividade sequestradora do DPPH desde 3.93 a 8.92%). A atividade antibacteriana de G. longissima é notável, não apresentando variação sazonal contra qualquer uma das bactérias testadas. De modo geral, G. longissima apresenta-se como uma potencial fonte de compostos biológicos ativos, com apreciável relevância em um vasto leque de aplicações biotecnológicas. Apesar de distintos, os resultados obtidos nos Capítulos Um e Dois devem ser considerados mutuamente, pois oferecem contribuições respeitantes a condições de crescimento para G. longissima, e um parecer sobre compostos fornecidos pela macroalga, que poderão eventualmente justificar o futuro cultivo em larga-escala dedicado a esta espécie.
- Growth of Arthrospira platensis under laboratory and outdoor conditions: assessment of the effects of light and different nutrient mediaPublication . Carneiro, João; Gomes, Sílvia; Freitas, Marta; Afonso, Clélia; Mouga, Teresa
- New applications for Gelidium corneum: Antimicrobial and antioxidant activity within a biorefinery conceptPublication . Mouga, Teresa; Cavaco, Mário; Duarte, Adriana; Correia, Ana Patrícia; Freitas, Marta V.; Bernardino, Susana; Afonso, CléliaThere are more than four hundred endogenous seaweeds that occur in Portugal, and red seaweeds (Rhodophyta) are the most abundant. Among these, Gelidium corneum, common in the Atlantic coast of Portugal, is currently being collected in the wild, in S. Martinho do Porto, exclusively for the extraction of agar. During the summer season this species is harvested from the bottom of the ocean, dried and sold, representing an important economic local activity. Yet, besides agar, this species is important for its bioactivities, namely for its antioxidant and antimicrobial capacities, thus most of the biomass is currently being disregarded as an important marine resource. Therefore, to further research the potential of G. corneum as a source of bioactive compounds, the biomass was seasonally harvested and characterized (protein, ash, moisture), and different extract were made (aqueous and ethanolic). These extracts were analyzed for the antioxidant potential (DDPH, ABTS, TPC and FRAP), and for antimicrobial capacity (against Escherichia coli, Bacillus subtilis, Candida albicans, Saccharomyces cerevisiae and Staphylococcus epidermidis). Preliminary results show that there are seasonal variations in the chemical composition of the biomass. Extracts tested also show interesting free radical scavenging capacity and antimicrobial activity against some of the strains tested. The attained results demonstrate that the biorefinery concept should be implemented to the agar industry, valuing the seaweeds’ biomass so to allow its use in other industries, such as textiles or cosmetics.
- Optimizing Growth Conditions and Biochemical Properties of Chondracanthus acicularis (Rhodophyta) in Laboratory SettingsPublication . Mouga, Teresa; Sousa, Andreia; Freitas, Marta; Afonso, CléliaThis study aimed to evaluate the laboratory cultivation of Chondracanthus acicu laris, focusing on key environmental parameters such as nutrient levels and light exposure. The results provide insights into the optimal growth conditions and biochemical com position of C. acicularis, which are crucial for its sustainable exploitation in industrial applications. Significant differences in the relative growth rate (RGR) and productivity (Y) were found between the different treatments. Seaweed grown on Provasoli (PES) Medium with white LED light and red LED light showed the best growth rates. Negative growth was observed in treatments with Nutribloom plus®, and blue LED light. The proximate composition analysis revealed a high moisture content across all treatments, with significant differences in ash and organic matter content between the treatments. The use of LED light played a crucial role in optimizing growth by influencing photosynthetic efficiency and pigment production. The proximate composition varied significantly between treatments, especially ash and organic matter. Light and nutrient conditions also influenced pigmenta tion and colour characteristics, with significant changes in phycoerythrin, phycocyanin, and chlorophyll concentration. PES treatments consistently showed the highest colour variation. These findings highlight the influence of environmental conditions on seaweed growth, productivity, pigmentation, and proximate composition, and provide valuable insights for optimized cultivation strategies.
- In vitro evaluation of the antibacterial and antioxidant activities of extracts of Gracilaria gracilis with a view into its potential use as an additive in fish feedPublication . Afonso, Clélia; Correia, Ana; Freitas, Marta; Mouga, Teresa; Baptista, TeresaFish in aquaculture systems are subject to several stressors that inhibit the immune response and potentiate the development of disease and increased mortality. The inclusion of additives in the fish diet, namely seaweeds or their extracts, that are natural sources of bioactive compounds can be an important tool for promoting the health and well-being of these animals. The present study aims at the development of sustainable and effective methodologies for the extraction of bioactive compounds of the red seaweed Gracilaria gracilis, exploring its antibacterial and antioxidant potential and considering its potential use as an additive for functional fish feeds. The yield of the extraction methods was evaluated upon the use of sequential solid–liquid extraction techniques with ethanol and water as solvents, different extraction temperatures (room temperature: 40ºC and 70ºC), and extraction time. The results demonstrated that the adoption extraction times of 30 min. at 40ºC provided higher yields. We also evaluated the antioxidant capacity and the antibacterial properties of the obtained extracts against different strains that cause fish diseases by disk diffusion and broth microdilution methods. The antioxidant activity was determined by the DPPH reducing capacity method and quantification of total polyphenols content (TPC).With these results, we can establish extraction procedures that allow the future use of G. gracilis extracts, with antibacterial and antioxidant effects in a safe and effective way.
- Identification of Gracilariaceae (Rhodophyta) of central Portugal by histological and genetic methodsPublication . Freitas, Marta V.; Simões, Marco; Valdez, Christian; Afonso, Clélia; Trindade, Beatriz G.; Correia, Ana; Baptista, Teresa; Mouga, TeresaThis study aims to identify different populations of Gracilariaceae collected from the central coast of Portugal through light microscopy, anatomical observations and genetic tools, essential approaches to correctly assign species identity. Samples were obtained from Ria de Aveiro (AV), Figueira da Foz (FFBC, FFMD), and Lagoa de Óbidos (LOBR, LOEV, LOBS). Although histological observations offered a visual representation of the characteristic pseudoparenchymatous organization, they did not allow a clear distinction among the species. The amplification of a ∼700 bp fragment of the mitochondrial cytochrome oxidase I gene, and its sequencing enabled us to assign the populations FFBC and LOBS to Gracilaria gracilis, and the populations AV, FFMD, LOBR, and LOEV to Agarophyton vermiculophyllum. This contribution will help phycologists to correctly identify the Portuguese populations of Gracilaria sensu lato at the species level, which will be crucial in ensuring that future studies and industrial exploration accurately target the correct species.
- Antioxidant and antimicrobial properties of selected red seaweeds from Central PortugalPublication . Freitas, Marta V.; Inácio, Leonardo G.; Ruas, Ana; Silva, Isabela A.; Mouga, Teresa; Pereira, Leonel; Afonso, CléliaThroughout the ages, macroalgae have provided humankind with elements beneficial to human health, and often with bioactive abilities. Yet, while today we fully acknowledge such potential, especially that of the most widely known species, an even greater number of species remain unaknowledged. This holds particularly true for the highly diverse phylum Rhodophyta (red seaweeds) and, therefore, the present study aims to unveil the antioxidant and the antimicrobial potential of twelve red seaweed species collected in central Portugal. Results obtained from the antioxidant assays ABTS and TPC highlighted the high scavenging capacity of the coralline algae Corallina officinalis, Ellisolandia elongata and Amphiroa rigida, and the high phenolic content of Porphyra umbilicalis, whereas the antimicrobial analyses through MIC determination emphasized the activities of Sphaerococcus coronopifolius and Mesophyllum lichenoides against, respectively, Bacillus subtilis and Saccharomyces cerevisiae. This study raised awareness of the bioactive potential waiting to be discovered regarding less known Rhodophyta species, such as Amphiroa rigida and Mesophyllum lichenoides. Therefore, we believe this study provides extra steps in pinpointing Rhodophyta species with bioactive potential, encouraging further studies tailored toward a biotechnological perspective, and, ultimately, influencing current perspectives regarding the exploration of seaweeds.
- Sabores do mar: algas edíveis do centro de PortugalPublication . Freitas, Marta v.; Pereira, Leonel; Afonso, Clélia; Mouga, TeresaDescrição das espécies alimentares da zona centro de Portugal