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Abstract(s)
As microalgas são reconhecidas como fonte de compostos bioativos de alto valor acrescentado, que possuem uma ampla gama de aplicações. Porphyridium cruentum é uma microalga vermelha que possui uma gama de constituintes intracelulares e extracelulares interessantes, como polissacáridos, ficobiliproteínas e ácidos gordos polinsaturados. A biomassa de P. cruentum foi produzida sob duas condições diferentes de concentração de NO3- , MN (6mM) e HN (18 mM) em diferentes escalas de produção: laboratorial e em fotobiorreatores flat panel (FBR FP), tendo sido recolhida no início da fase estacionária de crescimento. A biomassa produzida em FBR FP foi separada do meio de cultura através de ultrafiltração (UF) utilizando uma membrana polimérica de acetato de celulose (AC) de 139 kDa. A partir do meio de cultura recuperado, os polissacáridos extracelulares foram fraccionados também por UF através de duas membranas de AC com limite de exclusão molecular de 10 kDa e 4 kDa. De forma a avaliar a produção de compostos intracelulares nas diferentes condições de crescimento foram realizados dois métodos de extração: extração convencional em multi-etapas (ME) e extração assistida por micro-ondas (MAE). Os extratos resultantes foram avaliados quanto ao conteúdo em biomoléculas e propriedades antioxidantes. A biomassa produzida à escala laboratorial apresentou o maior conteúdo em biomoléculas intracelulares, sendo possível alcançar 1270,230 ± 105,960 mg de polissacáridos neutros/g biomassa, 81,263 ± 2,656 mg de polissacáridos sulfatados/g biomassa e 36,858 ± 0,702 mg de proteína total/g biomassa, obtido por ME. Já a biomassa produzida em FBR FP apresentou o maior conteúdo em compostos fenólicos totais e flavonóides totais, alcançando 8,665 ± 0,181 mg GAE/g biomassa e 51,782 ± 2,315 mg CE/g biomassa, respetivamente, obtido por MAE utilizando KOH 0,1 M como solvente. O extrato FHCl proveniente da ME realizada a MN1 foi ainda sujeito a fracionamento por cromatografia de troca iónica. De forma a identificar diferenças estruturais nos extratos, caracterizar parcialmente biomoléculas detetadas e avaliar as propriedades fotofísicas foram aplicadas as técnicas espetroscópicas, FTIR e espetroscopia de fluorescência, respetivamente.
Microalgae are recognized as a source of high added value bioactive compounds, which have a wide range of applications. Porphyridium cruentum is a red microalga that has a range of interesting intracellular and extracellular constituents such as polysaccharides, phycobiliproteins and polyunsaturated fatty acids. P. cruentum biomass was produced under two different conditions of NO3-, MN (6mM) and HN (18mM) at different production scales: laboratory and in flat panel photobioreactors (FBR FP), having harvested at the beginning of the stationary phase. The biomass produced in FBR FP was separated from the culture medium by ultrafiltration (UF) using a polymeric membrane of cellulose acetate (CA) with a MWCO of 139 kDa. From the recovered culture medium, extracellular polysaccharides were also fractionated by UF through two AC membranes with molecular exclusion limits of 10 kDa and 4 kDa. To evaluate the production of intracellular compounds under different growth conditions, two extraction methods were performed: conventional multi-step extraction (ME) and microwave-assisted extraction (MAE). The resulting extracts were evaluated for biomolecule content and antioxidant properties. Biomass produced on a laboratory scale showed the highest content of intracellular biomolecules, reaching 1270,230 ± 59,105,960 mg of neutral polysaccharides/g biomass, 81,263 ± 2,656 mg of sulfated polysaccharides/g biomass and 36,858 ± 0,702 mg of total protein/g biomass, obtained by ME. The biomass produced in FBR FP had the highest content of total phenolic compounds and total flavonoids, reaching 8,665 ± 0,181 mg GAE/g biomass and 51,782 ± 2,315 mg CE/g biomass, respectively, obtained by MAE using 0,1 M KOH as solvent. The FHCl extract from the ME performed on MN1 was further subjected to fractionation by ion exchange chromatography. To identify structural differences in the extracts, partially characterize detected biomolecules and evaluate the photophysical properties, spectroscopic techniques were applied, FTIR and fluorescence spectroscopy, respectively.
Microalgae are recognized as a source of high added value bioactive compounds, which have a wide range of applications. Porphyridium cruentum is a red microalga that has a range of interesting intracellular and extracellular constituents such as polysaccharides, phycobiliproteins and polyunsaturated fatty acids. P. cruentum biomass was produced under two different conditions of NO3-, MN (6mM) and HN (18mM) at different production scales: laboratory and in flat panel photobioreactors (FBR FP), having harvested at the beginning of the stationary phase. The biomass produced in FBR FP was separated from the culture medium by ultrafiltration (UF) using a polymeric membrane of cellulose acetate (CA) with a MWCO of 139 kDa. From the recovered culture medium, extracellular polysaccharides were also fractionated by UF through two AC membranes with molecular exclusion limits of 10 kDa and 4 kDa. To evaluate the production of intracellular compounds under different growth conditions, two extraction methods were performed: conventional multi-step extraction (ME) and microwave-assisted extraction (MAE). The resulting extracts were evaluated for biomolecule content and antioxidant properties. Biomass produced on a laboratory scale showed the highest content of intracellular biomolecules, reaching 1270,230 ± 59,105,960 mg of neutral polysaccharides/g biomass, 81,263 ± 2,656 mg of sulfated polysaccharides/g biomass and 36,858 ± 0,702 mg of total protein/g biomass, obtained by ME. The biomass produced in FBR FP had the highest content of total phenolic compounds and total flavonoids, reaching 8,665 ± 0,181 mg GAE/g biomass and 51,782 ± 2,315 mg CE/g biomass, respectively, obtained by MAE using 0,1 M KOH as solvent. The FHCl extract from the ME performed on MN1 was further subjected to fractionation by ion exchange chromatography. To identify structural differences in the extracts, partially characterize detected biomolecules and evaluate the photophysical properties, spectroscopic techniques were applied, FTIR and fluorescence spectroscopy, respectively.
Description
Trabalho final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica
Keywords
Microalgas vermelhas Porphyridium cruentum Ultrafiltração Compostos bioativos Propriedades antioxidantes Red microalgae Porphyridium cruentum Ultrafiltration Bioactive compounds Antioxidant properties
Citation
CINTRA, Carolina Leal - Produção, isolamento e caracterização de compostos bioativos da microalga vermelha porphyridium cruentum. Lisboa: Instituto Superior de Engenharia de Lisboa, 2022. Dissertação de Mestrado.