Tesis doctoral de Juan Maldonado Ortiz
In this work, the effect and capacity to capture heavy metals (pb and cu) of dif-ferent phototrophic and heterotrophic microorganisms have been studied through high-resolution microscopy techniques in order to select microorganisms as metal pollution indicators. for this purpose, different phototrophic microorganisms isolated from ebro delta microbial mats (an ecosystem declared as natural park in 1983) and cyanobacteria from the pasteur culture collection (pcc) have been selected. These mats, dominated by photosynthetic microorganisms like cyanobacteria and algae (primary producers in these habitats) can suffer pollution by toxic compounds such as oil or heavy metals. In this study, metals tested to select the bioindicators were lead (pb) and copper (cu), as both have been detected in the ebro river, and also because the former is very toxic, showing no biological function, while the latter, by contrast, is an essential element at low doses, while at high doses it is toxic. to determine the sensitivity to a metal (tolerance-resistance), confocal laser mi-croscopy coupled to a spectrofluorometric detector (clsm-¿scan) has been used. The results show that chroococcus sp. Pcc 9106 and de2009 microalgae show greater toler-ance to lead pb (0.5 mm) than oscillatoria sp. Pcc 7515 and spirulina sp. 6313 (0.1 mm). to determine the external and intracellular metal biocapture, scanning electron microscopy (sem), transmission electron microscopy (tem) and energy dispersive x-ray microanalysis (edx) coupled with these microscopes have been used, respectively. The results indicated that, all the microorganisms tested (both phototrophic and hetero-trophic) have capacity to accumulate pb and cu externally in the eps. finally, the analysis of ultrathin sections (tem-edx) shows that all the photo-trophic microorganisms studied accumulate pb in the polyphosphate inclusions (pp). by contrast, although the heterotrophic bacteria show these inclusions, they do not accumulate either of the two metals either in cytoplasm or in intracellular inclusions. once the effectiveness of these microscopy techniques has been shown both in microorganisms isolated from the natural environment and in those from the culture collection, the same tests have been carried out in microcosms in order to obtain good bioindicators of metal pollution, with the ultimate aim of applying them in the natural environment. In these experiments it has been shown that, as in cultures, the most abundant microorganisms selected in this artificial ecosystem, lyngbya-like and phor-midium-like (cyanobacteria), have the capacity to accumulate this metal both externally and internally, always in pp inclusions. considering all the results obtained it can be concluded that all cyanobacteria and de2009 microalga analysed could be considered good metal pollution indicators. However, oscillatoria sp. And microcoleus sp. Have been selected as the best indicators of metal pollution in the natural environment because: they are the most abundant, largest in size, tolerant to high concentrations of metals and, finally, capable of accumulating metal extra- and intracellularly.
Datos académicos de la tesis doctoral «Selection of phototrophic microorganisms for use as bioindicators of heavy metals in natural environments. optimization of high-resolution microscopy techniques«
- Título de la tesis: Selection of phototrophic microorganisms for use as bioindicators of heavy metals in natural environments. optimization of high-resolution microscopy techniques
- Autor: Juan Maldonado Ortiz
- Universidad: Autónoma de barcelona
- Fecha de lectura de la tesis: 25/07/2011
Dirección y tribunal
- Director de la tesis
- Isabel Esteve Martínez
- Tribunal
- Presidente del tribunal: neus Ferrer miralles
- María soledad Goñi urriza (vocal)
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- (vocal)