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Chlorella vulgaris: Influência da intensidade luminosa e exposição ao H2O2 sobre o crescimento e acumulação de lípidos e carotenoides
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Abstract(s)
Com origem há cerca de 2.500 milhões de anos, as microalgas podem ser encontradas em
quase todo o tipo de ambientes apresentando, deste modo, uma extensa biodiversidade
que possibilita a exploração de diferentes metabolitos por elas produzidos.
Atualmente, a exploração destes microrganismos abrange uma vasta área, que vai desde a
alimentação humana e animal até à farmacêutica. O seu interesse comercial é evidente,
produzindo-se cerca de 11 000 toneladas todos os anos.
Apesar dos avanços alcançados, persiste a necessidade de otimizar o processo como um
todo, para melhorar a sua viabilidade económica. Neste contexto, a otimização da extração
de produtos de elevado valor acrescentado, como a astaxantina, é uma das vias a seguir.
Este produto é produzido principalmente pela microalga Haematococcus pluvialis;
atualmente, são produzidas cerca de 300 toneladas por ano e o seu valor pode atingir os
6300€/kg. O presente trabalho visava trabalhar com a H. pluvialis e otimizar as suas
condições de crescimento e de extração de astaxantina. Durante os meses de novembro e
dezembro de 2019 realizaram-se alguns ensaios com esta microalga, que permitiram
identificar alguns fatores limitantes do crescimento, nomeadamente fosforo e luz. Com o
aparecimento da pandemia não foi possível manter a H. pluvialis em condições favoráveis,
tendo ocorrido contaminações por outros microrganismos que tornou inviável continuar
com esta microalga adquirida na Escócia. Face a isto, o trabalho orientou-se para a Chlorella
vulgaris na qual se aplicou a mesma estratégia: identificação das limitações ao crescimento;
aumento do crescimento suprindo as carências de fosforo e implementando um método que
permite fornecer a intensidade luminosa necessária, mesmo com elevadas concentrações de
biomassa; aplicação de condições de stress ( luz, carência de nutrientes e H2O2) e avaliação
do impacto na biomassa e nos correspondentes teores de carotenoides e lípidos.
Deste modo, foi realizado uma otimização que envolveu alterações no meio de cultura e,
posteriormente, foi analisado e caracterizado o efeito da intensidade luminosa ao longo do
tempo de cultura, sendo este um dos fatores limitantes na cultura.
O método proposto permitiu aumentar em 22% a quantidade de lípidos e em 51% a
quantidade de carotenos produzidos pelas células, tendo em conta o acréscimo de biomassa
obtido pelos métodos de cultura otimizados, quando comparados a um controlo.
Os resultados desta investigação permitem o desenvolvimento de métodos mais eficazes na
produção de biomassa, bem como a utilização de um método para a produção de compostos
de interesse, apresentando-se o peróxido de hidrogénio como um indutor de stress
Microalgae appeared around 2,500 million years ago. They can be found in almost all types of environments, thus presenting an extensive biodiversity that allows the exploration of different metabolites produced by them. Currently, the use of these microorganisms covers a wide area, ranging from human and animal food to pharmaceuticals. Being produced around 11,000 tonnes every year. Despite the advances achieved, there is still a need to optimize the process, to improve its economic viability. In this context, the optimization of the extraction of products with high added value, such as astaxanthin, is one of the ways to be followed. This product is mainly produced by the microalgae Haematococcus pluvialis; currently, about 300 tons are produced per year and their value can reach € 6300 / kg. The present work aimed to work with H. pluvialis and to optimize its conditions of growth and astaxanthin extraction. During the months of November and December 2019, some tests were carried out with H. pluvialis, which allowed to identify some limiting factors of growth, namely phosphorus and light. With the appearance of the pandemic, it was not possible to maintain H. pluvialis: contamination by other microorganisms occurred and it was impossible to continue the study. In view of this, the work was oriented towards Chlorella vulgaris in which the same strategy was applied: identification of growth limitations; increased growth, surpassing the phosphorus deficiencies and implementing a method that allows to provide the necessary light intensity, even with high concentrations of biomass; application of stress conditions (light, nutrients starvation and H2O2) and assessment of the impact on biomass and the levels of carotenoids and lipids. In this way, an optimization was carried out that involved changes in the culture medium and, later, the effect of light intensity over the culture time was analyzed and characterized, this being one of the limiting factors in the culture. The proposed method allowed to increase the amount of lipids by 22% and the amount of carotenes produced by cells by 51%, considering the increase in biomass obtained by the optimized culture methods, when compared to a control. The results of this investigation allow the development of more effective methods in the production of biomass, as well as the use of a method to produce compounds of interest, presenting hydrogen peroxide as a stress inducer.
Microalgae appeared around 2,500 million years ago. They can be found in almost all types of environments, thus presenting an extensive biodiversity that allows the exploration of different metabolites produced by them. Currently, the use of these microorganisms covers a wide area, ranging from human and animal food to pharmaceuticals. Being produced around 11,000 tonnes every year. Despite the advances achieved, there is still a need to optimize the process, to improve its economic viability. In this context, the optimization of the extraction of products with high added value, such as astaxanthin, is one of the ways to be followed. This product is mainly produced by the microalgae Haematococcus pluvialis; currently, about 300 tons are produced per year and their value can reach € 6300 / kg. The present work aimed to work with H. pluvialis and to optimize its conditions of growth and astaxanthin extraction. During the months of November and December 2019, some tests were carried out with H. pluvialis, which allowed to identify some limiting factors of growth, namely phosphorus and light. With the appearance of the pandemic, it was not possible to maintain H. pluvialis: contamination by other microorganisms occurred and it was impossible to continue the study. In view of this, the work was oriented towards Chlorella vulgaris in which the same strategy was applied: identification of growth limitations; increased growth, surpassing the phosphorus deficiencies and implementing a method that allows to provide the necessary light intensity, even with high concentrations of biomass; application of stress conditions (light, nutrients starvation and H2O2) and assessment of the impact on biomass and the levels of carotenoids and lipids. In this way, an optimization was carried out that involved changes in the culture medium and, later, the effect of light intensity over the culture time was analyzed and characterized, this being one of the limiting factors in the culture. The proposed method allowed to increase the amount of lipids by 22% and the amount of carotenes produced by cells by 51%, considering the increase in biomass obtained by the optimized culture methods, when compared to a control. The results of this investigation allow the development of more effective methods in the production of biomass, as well as the use of a method to produce compounds of interest, presenting hydrogen peroxide as a stress inducer.
Description
Keywords
Carotenos Chlorella Vulgaris Haematococcus Pluvialis Microalga Otimização Luminosa