2 research outputs found

    Optimization of FucoPol bioreactor production and exopolysaccharide applications

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    FucoPol is an exopolysaccharide (EPS) produced by the bacterium Enterobacter A47, composed of sugars (fucose, galactose, glucose and glucuronic acid) and acyl groups (succinyl, pyruvyl and acetyl), and with a high average molecular weight (>106 Da). The first main goal of this thesis was to investigate the effect of the phosphorus (P) concentration on FucoPol production. Production assays were performed under different concentrations of this nutrient: from 0.8 to 2.6 g.L-1(standard concentration). The conditions implemented did not affect Enterobacter A47 growth, but a reduction of the EPS synthesis was observed: 24% less polymer when 2 and 1.3 g.L-1 of P were used, and 44% for 0.8 g.L-1 of phosphorus. A slight reduction to 2.0 g.L-1 in the phosphorus concentration did not affect the polymer’s composition, neither the molecular weight. However, the EPS obtained from the assays with fewer P showed less fucose content and was richer in glucose. Secondly, this thesis aimed to assess the flocculation properties of FucoPol. The flocculation rate of FucoPol was determined using a kaolin clay suspension (5 g.L-1) in the presence of CaCl2. Flocculation rate values above 70% were achieved with a low bioflocculant dosage of 1 mg.L-1, for pH values in the range 3-5, and temperature within 15-20 ºC. The bioflocculant was also shown to be stable after freezing/thawing and heating up to 100 ºC, for 20 min. The work performed in this thesis also had as an objective to explore the metal binding efficiency of the polysaccharide. FucoPol revealed a good performance in the biosorption of cobalt, copper and zinc. The polysaccharide was an excellent biosorbent of lead so this metal was chosen for further studies, namely the impact of EPS dosage, Pb2+ initial concentration, pH and temperature. Optimal FucoPol concentration of 5 mg.L-1 was found to uptake 18645 mgmetal.g-1EPS from an 100 mg.L-1 Pb2+ solution, at pH 2.3. Moreover, FucoPol presented a great sorption performance in the range of temperatures between 5 and 45 oC

    Development of new bioactive materials based on microbial exopolysaccharides of marine origin

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    The arising of novel bio-based products and processes is vital for the sustainable development of society. The exploitation of marine resources towards the development of new ecological products with commercial interest is a promising solution. In this thesis, marine biodiversity was explored for the development of new and improved biomaterials and/or bioactive compounds based on marine exopolysaccharides (EPS). Marine microorganisms, including both microalgae and bacteria, were prospected for their EPS production capacity. The results obtained in this study showed that marine microalgae have an enormous potential as producers of EPS with unique chemical compositions, including high contents in sulphate and unusual sugars. These characteristics are often associated with biological activities, which supports the potential of microalgal EPS to be employed as bioactive compounds. Indeed, in this work, the EPS produced by microalga Heterocapsa AC210 demonstrated antioxidant and anti-inflammatory properties. Additionally, the EPS produced by bacteria isolated from unusual marine environments showed interesting compositions, including high uronic acids contents, and relevant functional properties. These biopolymers presented thickening, gel and film forming capacities, suggesting that they might be successfully used as structuring biomaterials. This work showed that it was possible to use low-cost feedstocks for the cultivation of the bacterium Alteromonas macleodii Mo169, resulting in higher productivities and distinctive EPS compositions. The EPS produced by this strain also revealed potential in the nanotechnology field, as it might be used for the ecological synthesis of gold, silver, and selenium nanoparticles with wound healing and antioxidant properties. Overall, this work supports that natural EPS bioprospected from marine microorganisms can be used for the development of bio-based products with application in high-value markets, thus, contributing to a sustainable future powered by marine biotechnology.O aparecimento de novos produtos e processos de origem biológica é vital para o desenvolvimento sustentável da sociedade. Uma solução promissora é a exploração dos recursos marinhos para o desenvolvimento de novos produtos ecológicos com interesse comercial. Esta tese explora a biodiversidade marinha com o objetivo de desenvolver novos biomateriais e/ou compostos bioactivos a partir de exopolissacáridos (EPS) marinhos. A capacidade de produzir EPS foi avaliada para vários microrganismos marinhos, incluindo microalgas e bactérias. Os resultados obtidos neste trabalho demonstraram que as microalgas marinhas têm um enorme potencial na produção de EPS com composições químicas únicas, que incluem um elevado conteúdo em sulfato e monossacáridos invulgares. Estas características estão frequentemente associadas a atividades biológicas, reforçando a ideia de que os EPS das microalgas têm potencial para serem utilizados como compostos bioactivos. De facto, neste trabalho, o EPS produzido pela microalga Heterocapsa AC210 demonstrou ter propriedades antioxidantes e anti-inflamatórias. Além disso, os EPS produzidos por bactérias isoladas de ambientes marinhos incomuns apresentaram composições interessantes, incluindo altos teores de ácidos urónicos, e propriedades funcionais relevantes. Estes biopolímeros mostraram ter capacidade espessante, bem como a capacidade de formar géis e filmes, o que sugere que possam ser utilizados como biomateriais estruturais. Este trabalho demonstrou ser possível utilizar substratos de baixo custo no cultivo da bactéria Alteromonas macleodii Mo169, o que resultou em produtividades superiores e EPS com composições distintas. O EPS produzido por esta cultura também revelou ter potencial na área da nanotecnologia, dado que pode ser utilizado na síntese ecológica de nanopartículas de ouro, prata e selénio com propriedades regenerantes e antioxidantes. No geral, este trabalho apoia a convicção de que os EPS naturais obtidos de microrganismos marinhos podem ser utilizados para o desenvolvimento de bioprodutos com aplicações em mercados de elevado valor comercial, contribuindo assim para um futuro sustentável baseado na biotecnologia marinha
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