Nitrogênio inorgânico intracelular : extração, papel fisiológico e acumulação por microalgas marinhas, em cultivos estanques

• Autor(a) principal: Sepúlveda, Paris Leonardo Lavín
• Data de Publicação: 2000
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal Fluminense (RIUFF)
• Texto Completo: https://app.uff.br/riuff/handle/1/21120
• topic: Amônia; Metodologias de extração; Microalgas; Nitrato; Nitrito; Nitrogênio; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA

Methods of extraction, changes in the concentrations over growth, and effects of culture conditions on intracellular inorganic nitrogen pools (IIN - ammonia, nitrite, and nitrate) were studied in nine species of marine microalgae in batch cultures. In the first part of this study the microalgae were analysed to compare three methods of extraction of IIN. One of the methods was developed in this study. The extraction of IIN occurs in an efficient way with the three methods for three of the species tested. However, for six species differences were found among methods, and better results were obtained with the new methodology. Microalgae accumulate inorganic forms of nitrogen in different proportions. The species showed higher concentrations of either ammonia or nitrate, and always lower concentrations of nitrite. Differences in the accumulation of IIN were great among species. Microalgae of smaller cellular volumes and greater surface : volume ratios tended to attain higher values of IIN per cubic micrometer (conversely in species of large cell volumes and small surface : volume ratios), with some exceptions. The input of CO2 into the cultures determined a decrease in the concentrations of IIN, favouring the assimilation of nitrogen, and generating an increase in the growth rates. High concentrations of IIN are characteristic in the exponential growth phase, but in some cases their occurrence may result of carbon deficiency.