DEMET - Artigos publicados em periódicos

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Navegando DEMET - Artigos publicados em periódicos por Autor "Amorim, Soraya Sander"

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    High manganese tolerance and biooxidation ability of Serratia marcescens isolated from manganese mine water in Minas Gerais, Brazil.
    (2017) Barboza, Natália Rocha; Morais, Mônica Mendes Cordeiro Araújo; Queiroz, Pollyana Santos; Amorim, Soraya Sander; Cota, Renata Guerra de Sá; Leão, Versiane Albis
    anganese is an important metal for the maintenance of several biological functions, but it can be toxic in high concentrations. One of the main forms of human exposure to metals, such as manganese (Mn), is the consumption of solar salt contaminated. Mn-tolerant bacteria could be used to decrease the concentration of this metal from contaminated sites through safer environmental-friendly alternative technology in the future. Therefore, this study was undertaken to isolate and identify Mn resistant bacteria from water samples collected from a Mn mine in the Iron Quadrangle region (Minas Gerais, Brazil). Two bacterial isolates were identified as Serratia marcescens based on morphological, biochemical, 16S rDNA gene sequencing and phylogeny analysis. Maximum resistance of the selected isolates against increasing concentrations of Mn(II), up to 1200 mg L-1 was determined in solid media. A batch assay was developed to analyze and quantify the Mn removal capacities of the isolates. Biological Mn removal capacities of over 55% were detected for both isolates. Whereas that mechanism like biosorption, precipitation and oxidation could be explaining the Mn removal, we seek to give an insight into some of the molecular mechanisms adopted by S. marcescens isolates. For this purpose, the following approaches were adopted: leucoberbelin blue I assay, Mn(II) oxidation by cell-free filtrate and electron microscopy and energy-dispersive X-ray spectroscopy analyses. Overall, these results indicate that S. marcescens promotes Mn removal in an indirect mechanism by the formation of Mn oxides precipitates around the cells, which should be further explored for potential biotechnological applications for water recycling both in hydrometallurgical and mineral processing operations.
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    Manganese (Mn2+) tolerance and biosorption by Meyerozyma guilliermondii and Meyerozyma caribbica strains.
    (2018) Amorim, Soraya Sander; Ruas, France Anne Dias; Barboza, Natália Rocha; Neves, Viviano Gomes de Oliveira; Leão, Versiane Albis; Cota, Renata Guerra de Sá
    Bioremediation of manganese (Mn) is notoriously difficult to achieve because of the high stability of Mn2+ in aqueous solutions. Regarding the biotechnology strategies for removal of Mn from water, the use of bioremediation by bacteria and fungi is well known, but little is known about how yeasts can participate in this process. Hence, the study’s aim was to isolate yeasts with the ability to remove Mn2+, also elucidate the mechanism related to Mn bioremediation. Two kinds of yeast organisms were isolated from Brazilian mining water and identified as Meyerozyma guilliermondii and Meyerozyma caribbica by biochemical and phylogenetic analyses. Both isolates survived and their colonies grew in up to 32 mM of Mn2+, and they were able to remove 100% of Mn2+ from the culture medium in small-scale batch experiments conducted overall 1-week period. It was observed that for both isolates the removal of Mn is independent of pH. Analysis by SEM/EDX revealed that the Mn was adsorbed by the cell walls of M. guilliermondii and M. caribbica in the biosorption assays in the biological removal of bound Mn2+. These results demonstrated that both yeasts, with living and dead biomass, have an excellent Mn2+ ion biosorption capacity, as demonstrated by kinetic equations, in which M. caribbica showed a higher velocity when compared to M. guilliermondii. (respectively 1.088 and 0.324 mgMn day−1). Taken together, our results showed that these two yeasts isolates have potential roles in developing new biotechnology applications related to Mn bioremediation from waters contaminated with this persistent ion.