Efeitos da intensidade luminosa, fontes de nitrogênio e níveis de ferro no crescimento de Cylindrospermopsis raciborskii (UFV-P01) (Nostocales, Cyanobacteria)

• Main Author: Leal, Tatiane Vilela Freitas
• Publication Date: 2006
• Format: Master thesis
• Language: por
• Source: LOCUS Repositório Institucional da UFV
• Download full: http://locus.ufv.br/handle/123456789/2574
• topic: Cylindrospermopsis raciborskii; Cianobactéria; Nutrientes; Cylindrospermopsis raciborskii; Cyanobacteria; Nutrients; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA::ECOLOGIA DE ECOSSISTEMAS

The effects of the interactions among different light intensities, sources of nitrogen (N) and concentration of iron (Fe) were investigated in isolated Cylindrospermopsis raciborskii (UFV-P01) in laboratory, a potentially toxic cyanobacteria obtained from a fish ponds belonging to the Zoology Department of Federal University of Viçosa (UFV), Brazil. The cyanobacteria growth was monitored through the production of biomass contents of chlorophyll a (Chl a), total protein and filament numbers. To support the evaluation, in this study, on the effects of the applied treatments, it was also determined the content of total carotenoid (CaT), the proportion of the pigments Chl a: CaT and the specific growth rates of the organism. Differentiated growth responses were presented by C. raciborskii when exposed to different light intensities, sources of N and concentration of Fe. It was observed, in this research, a significant increase in the C. raciborskii growth in all analysed dependent variable (Chl a, total protein and filament number) independently of the N source and Fe levels applied, under light intensities of 128 µmol of photons m-2 s-1 (high light). In these growth conditions, a large concentration of CaT was observed in the cells of C. raciborskii, suggesting an adaptive strategy and a protection against photooxidation, making it possible for the organism to grow under high light intensity. Significant reduction in several parameters used to evaluate the growth of C. raciborskii were registered when the primary N source was the NH4 N associated to 900 µg L -1 of Fe ( production of Chl a, number of filaments, proportion of Chl a: CaT and growth rates, stood up in this treatment). When the supplement of N was NO3 N, the increase of the concentration of Fe in the medium did not result in any differentiated responses of growth when the same parameters were evaluated. The variation in the production of CaTs and total protein was also influenced by the treatments of Fe in the function of the time. Therefore, in treatments of larger concentrations of Fe, smaller was the production of carotenoids and total proteins found in the filaments of C. raciborskii (UFV P01).