Browsing by Author "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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    Isolamento e caracterização de leveduras com potencial para biorremoção do manganês.
    (2014) Amorim, Soraya Sander; Cota, Renata Guerra de Sá
    O processo de oxidação biológica do manganês (Mn) já é conhecido para bactérias e fungos, entretanto, ainda não é conhecida a participação de leveduras neste processo. Para investigar esta hipótese, o objetivo geral desse trabalho foi isolar leveduras e avaliar capacidade de oxidar o Mn(II). Inicialmente oito leveduras foram isoladas a partir de água de mina brasileira e cultivadas em meio YPD contendo de 1 a 54mM de Mn(II). Foi observado crescimento de leveduras em até 32mM deste íon. Também observou-se alteração na morfologia da colônia, escurecimento do meio de cultura e/ou escurecimento das colônias, sugerindo a capacidade de oxidar o Mn(II). Posteriormente os isolados foram caracterizados pelo perfil de assimilação de fontes de carbono (Auxanograma), os quais mostraram que dentre as oito leveduras isoladas, três eram Candida guilliermondii e cinco Rhodotorula mucilaginosa. Para confirmar a identificação das espécies, foi utilizada a estratégia de sequenciamento e análise filogenética da região ITS1–5.8S-ITS2. Os resultados confirmaram a identificação dos isolados de R. mucilaginosa, enquanto que os três isolados previamente identificadas como C. guilliermondii foram reclassificados em Meyerozyma gulliermondii (teleomorfo de C. guilliermondii) e Meyerozyma caribbica (teleomorfo de Candida fermentati). A seguir, foram realizados ensaios para avaliar a capacidade dos isolados de remover o íon Mn(II). Para isso foi utilizado meio YPD contendo 0,91mM do íon Mn(II), sendo avaliados durante sete dias: o crescimento das leveduras, pH e o decaimento do Mn (II), medido por espectrometria de emissão atômica com fonte plasma. M. guilliermondii e M. caribbica foram capazes de remover 100% do Mn(II) presente no meio de cultivo, enquanto R. mucilanigonosa removeu 10%. Não foi observado aumento do pH durante os ensaios, sugerindo que a remoção do Mn(II) foi biológica. A seguir, os ensaios foram reproduzidos nas mesmas condições e as leveduras, submetidas a microscopia eletrônica de varredura acoplada a microanálise de EDS. Os dados sugerem alteração na textura das células e o revestimento da parede celular com Mn para os isolados M. guilliermondii e M. caribbica. Também foram analisadas colônias mantidas em placas contendo 32mM de Mn(II) evidenciando que as leveduras foram capazes de oxidar e adsorver o Mn que estava no meio de cultura. Tomados em conjunto, os dados obtidos neste trabalho permitem concluir que M. guilliermondii e M. caribbica possuem um importante papel no ciclo biogeoquímico do manganês.
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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.
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    Rhodotorula mucilaginosa isolated from the manganese mine water in Minas Gerais, Brazil : potential employment for bioremediation of contaminated water.
    (2020) Ruas, France Anne Dias; Amorim, Soraya Sander; Leão, Versiane Albis; Cota, Renata Guerra de Sá
    Manganese (Mn) is an essential heavy metal for living organisms. However, they tend to accumulate the excess of this element causing health problems. The increase of the environmental contamination by this heavy metalis mainly due to mining practices. This work aimed to isolate yeast from mining waters to evaluate its ability of removing Mn2+ ions for the development of further biotechnological and bioremediation applications. The growing interest of this study is because it could be effective in the biological treatment of contaminated water, which remains a major challenge for industry and environment. Yeasts were initially isolated from mining water and grown in YPD medium containing 1 to 54 mM Mn2+. Subsequently, the isolates were characterized biochemically and phylogenetically. Then, we evaluate the ability of the isolates of removing Mn2+ ion by SEM scanning electron microscopy coupled with SEM/EDX. Our results showed yeast growth up to 32 mM. There was no pH increase along the tests, suggesting a biological Mn2+ removal. Taken together, the morphological changes in the colony and the darkening of the culture medium suggest the yeast’s ability of oxidizing Mn2+. Five isolates remove these ions considerably, identified as Rhodotorula mucilaginosa. SEM/EDX analysis shows the ability to oxidize and adsorb Mn. The data obtained in this work allows us to conclude that R. mucilaginosa has an important role in the biogeochemical cycle of manganese and present potential biotechnological applications for bioremediation of water contaminated with Mn2+ ions.