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Cultivo da microalga Scenedesmus sp. utilizando um fotobiorreator e resíduos agroindustriais para obter biomassa
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Abstract(s)
Nesta investigação foi estudado o crescimento da microalga Scenedesmus obliquus com foco na produtividade em biomassa e nas condições de cultivo. Para além do crescimento autotrófico da microalga, foi avaliado o seu crescimento mixotrófico na presença de diferentes resíduos agroindustriais, da indústria do tomate e da indústria vinícola, com o objetivo de tornar a produção da microalga mais económica, enriquecer a biomassa produzida e valorizar os resíduos, contribuindo para a gestão adequada dos mesmos.
Verificou-se um aumento na produtividade de biomassa quando se recorreu ao crescimento mixotrófico e, quanto maior a quantidade de resíduo no meio de cultivo, maior o estímulo no crescimento da microalga. O resíduo que se mostrou ser mais promissor foi o com origem no tomate (peles, sementes e polpa) que, quando usado na forma de xarope, substituiu 40% do meio de cultivo convencional. Nestas condições, a taxa de crescimento e a produtividade aumentaram significativamente e o tempo de duplicação diminuiu. O pH ácido característico dos resíduos, bem como a presença de uma baixa salinidade não mostraram ser fatores negativos nem limitativos para o crescimento da microalga pois esta demonstrou ser muito tolerante a meios de cultivo alternativos. O teor de proteína e o teor de açúcares totais aumentaram cerca de 4,6 mg/g e 27,6 mg/g, respetivamente, na biomassa mixotrófica seca em comparação com a biomassa autotrófica.
In this investigation, the growth of the microalgae Scenedesmus obliquus was studied with a focus on biomass productivity and cultivation characteristics. In addition to the autotrophic growth of microalgae, myxotrophic growth was evaluated in the presence of different agro- industry waste, from the tomato industry and the wine industry, with the objective of making the production of the microalgae more economical, enriching the biomass produced and to value these residues and contribute to the proper management of waste. Myxotrophic growth increased biomass yield and the increase in the amount of waste in the culture medium resulted in greater stimulation of microalgae growth. The residue that proved to be the most promising were from tomato (skins, seeds, and pulp), which when used in the form of syrup replaced 40% of the conventional culture medium. Under these conditions, the growth and productivity rate increased significantly, and the duplication time decreased. The acidic pH characteristic of the residues, as well as the presence of a low salinity, were not shown to be negative or limiting factors to the growth of the microalgae because it proved to be very tolerant to alternative culture media. Protein content and total sugar content increased by approximately 4,6 mg/g and 27,6 mg/g, respectively, in dry myxotrophic biomass compared to autotrophic biomass.
In this investigation, the growth of the microalgae Scenedesmus obliquus was studied with a focus on biomass productivity and cultivation characteristics. In addition to the autotrophic growth of microalgae, myxotrophic growth was evaluated in the presence of different agro- industry waste, from the tomato industry and the wine industry, with the objective of making the production of the microalgae more economical, enriching the biomass produced and to value these residues and contribute to the proper management of waste. Myxotrophic growth increased biomass yield and the increase in the amount of waste in the culture medium resulted in greater stimulation of microalgae growth. The residue that proved to be the most promising were from tomato (skins, seeds, and pulp), which when used in the form of syrup replaced 40% of the conventional culture medium. Under these conditions, the growth and productivity rate increased significantly, and the duplication time decreased. The acidic pH characteristic of the residues, as well as the presence of a low salinity, were not shown to be negative or limiting factors to the growth of the microalgae because it proved to be very tolerant to alternative culture media. Protein content and total sugar content increased by approximately 4,6 mg/g and 27,6 mg/g, respectively, in dry myxotrophic biomass compared to autotrophic biomass.
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Keywords
Microalga Biomassa Produtividade Crescimento mixotrófico Resíduos agroindustriais Microalgae Biomass Productivity Myxotrophic growth Agro-industrial waste