Publicação
Development of fermentation process for fungal fucoidanases production
| Resumo: | This thesis is focused in the development of an integral bioprocess for fungal fucoidanases production, in order to develop new strategies of fermentative conditions and parameters. In the recent years, the interest in the research field of fucoidans and fucoidanases has strongly increased due to the high potential in medical exploitation of fucoidans and its degradation products. Fucoidans are highly sulfated polysaccharides of brown algae widely used in fields as food and beverage, pharmacy, health medicine and cosmetics, due to their important biological properties as antitumoral, anticoagulant and antiviral activities. Enzymes with known specificities that catalyze the degradation of fucoidan are important tool for studying the relation between structure and biological role of this class of polysaccharide. Firstly, Aspergillus niger PSH, Mucor sp. 3P, and Penicillium purpurogenum GH2 were selected among several fungal strains, isolated from Northeast Mexican desert, for their fucoidan hydrolyzing ability, by measuring the strains kinetic and morphometric behavior over plate assays containing fucoidan as target polysaccharide and testing different nitrogen sources. Furthermore, submerged fermentations testing the synergy of fucoidan with others sugars for inducing high enzyme titles showed that A. niger PSH synthesized the highest titles of sulfated fucan-degrading enzymes with the culture media of fucoidan-sucrose. Secondly, Fucus vesiculosus algae were collected at Praia Norte, Viana de Castelo, Portugal, for hydrothermal extraction of sulfated polysaccharides (fucoidan) using microwave and autohydrolysis processes. Experimental designs were applied evaluating different conditions of temperature/ pressure, time and alga/water ratio to establish a condition to maximize the extraction results. For microwave assisted extraction at 120 psi, 1 min and 1:25 alga:water rate was the best condition for the fucoidan recovery (18%); whereas the extraction by autohydrolysis showed optimal yield at 180 °C for 20 min (16.5% w/w). The obtained products were characterized and it was verified the presence of fucose as the main constituent of these polysaccharides and a SO3 content higher than 20%. Moreover, as fucoidan is said to possess so many interesting bioactivities, the extracted products were analyzed for antioxidant activity, displaying a strong free radical scavenging effect; this behavior is possibly associated with the high content of sulphate groups. Finally, the solid stated fermentation (SSF) system was assessed for the induction of fucoidanases using the selected fungal strains and the Fucus vesiculosus algae, obtained after both hydrothermal extraction. A rotational drum bioreactor was designed to carry out the culture experiments. The results showed that the maximum fucoidanase activity was obtained with Mucor sp. 3P and algae after autohydrolysis pre-treatment production (3.82 U L-1); also the mixture of the solids showed to influence in the induction of the enzyme production. Moreover, a SSF scale up experiments showed that controlling the moisture content and the addition of inert support on algae substrates increment the enzyme production (9.62 U L-1). These results indicate, that the fucoidan hydrolytic enzyme can be extracellular, induced by a solid substrate rich of fucose and fucoidan. In general, with the established and developed methods of this thesis was possible to determine the solid state fermentation parameters for fucoidan hydrolytic enzyme production using terrestrial fungal strains and also allowed to set up the extraction conditions and physicochemical characteristics for the production of sulfated fucans by environmental friendly process. This opens up new vistas to modify fucoidan and to develop the postulated bioactive potentials. |
|---|---|
| Autores principais: | Rodríguez-Jasso, Rosa María |
| Ano: | 2012 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | This thesis is focused in the development of an integral bioprocess for fungal fucoidanases production, in order to develop new strategies of fermentative conditions and parameters. In the recent years, the interest in the research field of fucoidans and fucoidanases has strongly increased due to the high potential in medical exploitation of fucoidans and its degradation products. Fucoidans are highly sulfated polysaccharides of brown algae widely used in fields as food and beverage, pharmacy, health medicine and cosmetics, due to their important biological properties as antitumoral, anticoagulant and antiviral activities. Enzymes with known specificities that catalyze the degradation of fucoidan are important tool for studying the relation between structure and biological role of this class of polysaccharide. Firstly, Aspergillus niger PSH, Mucor sp. 3P, and Penicillium purpurogenum GH2 were selected among several fungal strains, isolated from Northeast Mexican desert, for their fucoidan hydrolyzing ability, by measuring the strains kinetic and morphometric behavior over plate assays containing fucoidan as target polysaccharide and testing different nitrogen sources. Furthermore, submerged fermentations testing the synergy of fucoidan with others sugars for inducing high enzyme titles showed that A. niger PSH synthesized the highest titles of sulfated fucan-degrading enzymes with the culture media of fucoidan-sucrose. Secondly, Fucus vesiculosus algae were collected at Praia Norte, Viana de Castelo, Portugal, for hydrothermal extraction of sulfated polysaccharides (fucoidan) using microwave and autohydrolysis processes. Experimental designs were applied evaluating different conditions of temperature/ pressure, time and alga/water ratio to establish a condition to maximize the extraction results. For microwave assisted extraction at 120 psi, 1 min and 1:25 alga:water rate was the best condition for the fucoidan recovery (18%); whereas the extraction by autohydrolysis showed optimal yield at 180 °C for 20 min (16.5% w/w). The obtained products were characterized and it was verified the presence of fucose as the main constituent of these polysaccharides and a SO3 content higher than 20%. Moreover, as fucoidan is said to possess so many interesting bioactivities, the extracted products were analyzed for antioxidant activity, displaying a strong free radical scavenging effect; this behavior is possibly associated with the high content of sulphate groups. Finally, the solid stated fermentation (SSF) system was assessed for the induction of fucoidanases using the selected fungal strains and the Fucus vesiculosus algae, obtained after both hydrothermal extraction. A rotational drum bioreactor was designed to carry out the culture experiments. The results showed that the maximum fucoidanase activity was obtained with Mucor sp. 3P and algae after autohydrolysis pre-treatment production (3.82 U L-1); also the mixture of the solids showed to influence in the induction of the enzyme production. Moreover, a SSF scale up experiments showed that controlling the moisture content and the addition of inert support on algae substrates increment the enzyme production (9.62 U L-1). These results indicate, that the fucoidan hydrolytic enzyme can be extracellular, induced by a solid substrate rich of fucose and fucoidan. In general, with the established and developed methods of this thesis was possible to determine the solid state fermentation parameters for fucoidan hydrolytic enzyme production using terrestrial fungal strains and also allowed to set up the extraction conditions and physicochemical characteristics for the production of sulfated fucans by environmental friendly process. This opens up new vistas to modify fucoidan and to develop the postulated bioactive potentials. |
|---|