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Avaliação do efeito dos polifenóis de efluentes da produção de vinho tinto no crescimento microbiano
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Abstract(s)
O projeto REDWine tem como principal objetivo a utilização do dióxido de carbono
biogénico (CO2) do processo de fermentação do vinho e dos efluentes líquidos da
indústria vinícola para a produção de microalgas Chlorella e sua posterior valorização
em produtos alimentares, cosméticos e agrícolas. Este trabalho visa estudar o efeito
dos polifenóis de efluentes da produção de vinho tinto no crescimento das microalgas,
pois essas substâncias podem ter um efeito inibidor do crescimento dos
microrganismos.
Com a finalidade de desenvolver o tema acima referido, começou por se estudar o
crescimento da microalga Chlorella vulgaris em meio inorgânico completo (MCV).
Durante essa monitorização, procedeu-se diariamente ao registo da intensidade
luminosa e da temperatura ambiente, para além da recolha de amostras das soluções
resultantes para medir o pH e a densidade ótica a 590 nm, para observar ao
microscópio o desenvolvimento celular. Posteriormente, foram desenvolvidos mais 3
ensaios, onde foi utilizado o ácido gálico, como representante dos polifenóis presentes
nos efluentes, com o objetivo de estudar o desenvolvimento da microalga perante
diferentes concentrações desse polifenol (0-600 mg/L). O procedimento foi
semelhante ao do ensaio de referência, com a adição da contagem de células em
algumas amostras recolhidas. A seguir, o sobrenadante das amostras diárias
selecionadas foi analisado pela mistura com as soluções de carbonato de sódio e de
Folin-Ciocalteau, medindo-se a absorvância a 765 nm com o objetivo de quantificar
os polifenóis totais e assim obter a variação temporal, tendo como base a reta de
calibração do ácido gálico realizada. Por fim, procedeu-se à amostragem de várias
soluções aquosas com diferentes concentrações de ácido gálico (até 1260 mg/L) para
medir a absorvância a 590 nm num período de 24 horas, com o propósito de avaliar o
efeito de acastanhamento nos meios com o polifenol, sendo que esses valores foram
aproveitados para realizar a correção da D.O. de um dos testes anteriores.
Relativamente aos resultados obtidos, foi possível concluir que, principalmente pela
visualização das curvas de crescimento e respetivas taxas e também do
acastanhamento ocorrido nos meios, o polifenol provocou um atraso no crescimento
das microalgas diretamente proporcional com a concentração utilizada, tendo levado
à morte celular por excesso de concentração, pelo facto de ter induzido a formação
excessiva de espécies reativas de oxigénio por meio da sua fotodegradação.
The REDWine project’s main objective is the use of biogenic carbon dioxide (CO2) from the wine fermentation process and from the wine industry’s liquid effluents to produce Chlorella microalgae and their subsequent valorisation into food, cosmetic and agricultural products. This work aims to study the effect of polyphenols from red wine production effluents on the growth of microalgae, because those substances may have an inhibitory effect on the growth of microorganisms. In order to develop the above-mentioned theme, it started by studying the growth of the Chlorella vulgaris microalgae in a complete inorganic medium (MCV). During this monitorization, the light’s intensity and ambient temperature were recorded daily, in addition to taking samples of the resulting solutions to subsequently measure pH and optical density at 590 nm, to observe cell development under a microscope. Three more tests were carried out afterwards, using gallic acid as a representative of the polyphenols present in the effluent, with the aim to study the development of the microalgae at different concentrations of this polyphenol (0-600 mg/L). There, the procedure was similar to that of the reference test, with the addition of the cell counting in some of the taken samples. Next, the supernatant of selected daily samples was analysed by mixing them with the sodium carbonate and Folin-Ciocalteau solutions, measuring the absorbance at 765 nm in order to quantify the total polyphenols and thus obtain the temporal variation, based on the realized gallic acid’s calibration line. Finally, the sampling of several aqueous solutions with different concentrations of gallic acid (up to 1260 mg/L) was carried out to measure the absorbance at 590 nm over a period of 24 hours, with the purpose of evaluating the browning effect of the media containing the polyphenol, being that these values were used to correct the O.D. of one of the previous tests. In relation to the obtained results, it was possible to conclude that, by visualising the growth curves and their respective rates and the browning in the media, the polyphenol caused a directly proportional delay in the microalgae’s growth to its used concentration, having led to cell death due to excess concentration, because it has led to an excessive formation of reactive oxygen species through its photodegradation
The REDWine project’s main objective is the use of biogenic carbon dioxide (CO2) from the wine fermentation process and from the wine industry’s liquid effluents to produce Chlorella microalgae and their subsequent valorisation into food, cosmetic and agricultural products. This work aims to study the effect of polyphenols from red wine production effluents on the growth of microalgae, because those substances may have an inhibitory effect on the growth of microorganisms. In order to develop the above-mentioned theme, it started by studying the growth of the Chlorella vulgaris microalgae in a complete inorganic medium (MCV). During this monitorization, the light’s intensity and ambient temperature were recorded daily, in addition to taking samples of the resulting solutions to subsequently measure pH and optical density at 590 nm, to observe cell development under a microscope. Three more tests were carried out afterwards, using gallic acid as a representative of the polyphenols present in the effluent, with the aim to study the development of the microalgae at different concentrations of this polyphenol (0-600 mg/L). There, the procedure was similar to that of the reference test, with the addition of the cell counting in some of the taken samples. Next, the supernatant of selected daily samples was analysed by mixing them with the sodium carbonate and Folin-Ciocalteau solutions, measuring the absorbance at 765 nm in order to quantify the total polyphenols and thus obtain the temporal variation, based on the realized gallic acid’s calibration line. Finally, the sampling of several aqueous solutions with different concentrations of gallic acid (up to 1260 mg/L) was carried out to measure the absorbance at 590 nm over a period of 24 hours, with the purpose of evaluating the browning effect of the media containing the polyphenol, being that these values were used to correct the O.D. of one of the previous tests. In relation to the obtained results, it was possible to conclude that, by visualising the growth curves and their respective rates and the browning in the media, the polyphenol caused a directly proportional delay in the microalgae’s growth to its used concentration, having led to cell death due to excess concentration, because it has led to an excessive formation of reactive oxygen species through its photodegradation
Description
Keywords
Projeto REDWine Microalgas Chlorella vulgaris Ácido gálico Taxa de crescimento REDWine project Chlorella vulgaris microalgae Gallic acid Growth rate