Marine and Environmental Sciences Centre

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Publications

Producing cyanobacteria to use as biostimulants

Publication . Mouga, Teresa; Simões, Fátima; Moreira, Vitória; Martins, Alice; Ferreira, Carolina; Ramos, Rute; Afonso, Clélia

By 2050, the world’s population will reach about 10 billion people, which will the need for food by about 60% more than is available today. To meet this need, new processes are emerging to allow more efficient and sustainable intensification of agriculture. In this context, the use of biostimulants has received increasing attention, due to their ability to improve plant quality and yield, stress tolerance, and/or improve the availability of nutrients in the soil. When it comes to Cyanobacteria, the preferred ones are N2-fixing species, which increase organic nitrogen in the soil, and produce hygroscopic exopolysaccharides, which alter the distribution of water by reducing soil hydrophobicity. Therefore, they decrease soil evaporation and retain moisture, improving soil stability. Wild strains of filamentous N2 fixing Nostoc 135, Nostoc 136, Nostoc 137, and Anabaena 4, provided by Alga2O Lda., were grown in the laboratory with the aim of selecting those that presented the necessary physiological characteristics to be efficiently grown in the laboratory. Therefore, the growth rate, productivity, and exopolysaccharides (EPS) contents were analysed. The EPS obtained from each strain culture (3% g/L) was applied to lettuce seeds (Lactuca sativa), to determine the germination rate, primary root length and number of primary leaves produced. As confirmed by other authors, Cyanobacteria are interesting biostimulants regarding germination rates. Other effects to be tested in the future are heat and drought tolerance, water, nutrients, essential oil, and pigment content, all of which are positive aspects that have been previously reported for other Nostoc and Anabaena species.

2023Conference object

Restricted access

The microalga Dunaliella and its applications: a review

Publication . Barbosa, Miguel; Inácio, Leonardo Garcia; Afonso, Clélia; Maranhão, Paulo

and industry. The high adaptability of Dunaliella to high salinity, as well as its fast growth and production of several metabolites have triggered interest. The attention of industry relates to its ability to synthesize several high-value compounds, such as β-carotene, lipids, glycerol, vitamins, and proteins. In addition, due to its tolerance to high salinity, contamination is reduced, and it can grow in open systems. Dunaliella salina can accumulate up to 25% dry weight in lipids and is the most efficient natural source of β-carotene. This review highlights the general characteristics of the genus, associated with its history, morphology, reproduction, occurrence, and taxonomy. The metabolic pathways for carotenoid and lipid synthesis are described. Relevant information on the most common strains is provided as well as the most widely used growth systems and conditions, and the expression systems under development. Applications of Dunaliella in several areas of the industry are also highlighted. Thus, this review can serve as a basis for future work and for the development of environmentally friendly, simple, and highly cost-effective production methods.

2023Journal article

Open access

Development and characterization of flms for food application incorporating Porphyran extracted from Porphyra dioica

Publication . Teles, Marco; Adão, Pedro; Afonso, Clélia; Bernardino, Raul; Guedes, Mafalda; Baptista, Ricardo; Bernardino, Susana

Non-biodegradable plastic is one of the biggest environmental problems of our lifetime and, considering the present societal needs, it will get worse. Consequently, there is an urgent need to develop sustainable and renewable alternatives to plastic, such as plastic-like materials obtained from biodegradable polymers, namely sulfated polysaccharides, considered one of the most viable alternatives. There is also a need to obtain these materials in an environmentally and economically sustainable way. The hereby developed process of obtaining film-forming solutions from semi-refined porphyran (PorphSR) uses a green solvent (hot water) with a high extraction yield of semi-refined porphyran (26.66 +- 0.27%) in a reproducible way and with low levels of contaminants. The obtained semi-refined porphyran showed good antioxidant potential in all tests performed: HPSA (D0.066 +- 0.002), DPPH (2.23 +- 0.78%), FRAP (0.420 +- 0.014 eq. ascorbic acid ug mg-1 of extract) and ABTS (20.46 +- 0.90%). After being cast into films, the most notable antioxidant properties were those of the semi-refined porphyran in the DPPH, FRAP and ABTS assays and of the pectin, (PorphSR_PcT and PorphSR_PcT_Gly) in the HPSA assay. Morphologically, the films showed relatively homogeneous and low roughness surfaces. It is concluded that the described method to obtain semi-refined porphyran is feasible and reproducible, and that the developed films, mainly PorfP2_PcT_Gly, proved to be a potential candidate for non-biodegradable plastic substitutes.

2021Journal article

Open access

Genetic identification and comparative study on life history parameters of two strains belonging to Brachionus plicatilis species complex (Rotifera: Monogononta)

Publication . Granada, Luana; Lemos, Marco F.L.; Bossier, Peter; Novais, Sara C.

The rotifer Brachionus plicatilis is an important species for aquaculture, due to its use as food for bivalves, and fish and crustaceans larvae in hatcheries. However, being a species complex, it has become increasingly important to catalogue and describe the species and biotypes that constitute this complex. Therefore, the purpose of this study was to genetically identify two morphologically identical strains and evaluate their suitability to be used in aquaculture under the studied conditions. A correct identification and knowledge of life history characteristics of the biotypes and isolated strains is vital to avoid mass mortalities in aquaculture and to better interpret the responses of the organisms when these are used as a bioindicator and model for ecotoxicology. Strains MRS10 and IBA3 were identified as B. koreanus and, even though they have been maintained under the same laboratory conditions for several years, significant differences in several life history parameters were observed. A life table assay showed IBA3 rotifers to be larger at first reproduction, and to have longer post-reproductive period and mean lifespan. On the other hand, MRS10 rotifers produced less non-viable eggs and had higher population growth rate. Both strains showed to be a potential model for ecotoxicological and molecular studies, mainly due to the ease of maintenance, short generation time, and reproduction via parthenogenesis. However, MRS10 might present better characteristics than IBA3 to be reared in aquaculture as live food.

2022Journal article

Restricted access

High dietary protein, n − 3/n − 6 ratio and β-carotene enhances Paracentrotus lividus (Lamarck, 1816) larval development

Publication . Gomes, Ana S.; Lourenço, Sílvia; Santos, Pedro M.; Neves, Marta; Adão, Pedro; Tecelão, Carla; Pombo, Ana

The nutritional characteristics of microalgae affect the growth, survival and fatty acid composition of sea urchin larvae. This study aimed to evaluate the influence of nutritive characteristics of single microalgal diets in Paracentrotus lividus (Lamarck, 1816) larval development, growth, and condition. Larvae of P. lividus were fed with three monospecific microalgal diets, Rhodomonas sp. (Rho), Dunaliella tertiolecta (Duna) and the diatom Chaetoceros calcitrans (Chae), and their development and growth were analysed until competence. Additionally, the fatty acid (FA) profile of larvae was analysed at competence and compared with the FA profile of the correspondent diet. The three groups of larvae attained competence simultaneously with differences in growth performance. The larvae fed with Chae attained the largest stomach and the shortest post-oral arm. The larvae were able to accumulate long-chain polyunsaturated fatty acids (PUFA), such as docosahexaenoic (DHA, C22:6n − 3), eicosapentaenoic (EPA, C20:5n − 3) and arachidonic (ARA, C20:4n − 6) acids, either by assimilation and retention of dietary FA or by the synthesis from α-linolenic acid (ALA, C18:3n − 3) and linoleic acid (LA, C18:2n − 6). Furthermore, the low DHA/EPA ratio and high EPA/ARA and n − 3/n − 6 ratios of Rho and Chae and the high levels of the β-carotene present in Chae improved larval growth and development. In conclusion, the results indicated that of the three microalgal diets tested, C. calcitrans provided important nutritional characteristics, especially in terms of FA composition and carotenoids, improving P. lividus larval growth and condition.

2022Journal article

Open access