Identificação de micro-organismos presentes em sistemas de biolixiviação de cobre a 35 e 50°C

Abstract

RESUMO A biolixiviação de minérios de baixo teor e com elevado conteúdo de impurezas tem se mostrado alternativa importante para o aproveitamento destes, uma vez que a recuperação do metal por métodos pirometalúrgicos convencionais mostra-se economicamente inviável. A identificação e quantificação dos micro-organismos capazes de promover a biolixiviação mostram-se estratégicas para alcançar bons rendimentos no controle do processo e na recuperação de metais. Nesse sentido, as técnicas de biologia molecular são as ferramentas mais utilizadas para tal propósito. Este trabalho, utilizando técnicas de reação em cadeia da polimerase (PCR), polimorfismos de comprimento dos fragmentos de restrição (RFLP) e reação em cadeia da polimerase seguida de eletroforese em gel com gradiente desnaturante (PCR-DGGE), mostrou que a diversidade nas colunas de biolixiviação de cobre estudadas é baixa e que a temperatura é importante na manutenção de determinadas espécies, havendo predominância de Acidithiobacillus ferroxidans a 35°C e de Sulfobacillus thermosulfidooxidans a 50°C.

Column Bioleaching of Fluoride-Containing Secondary Copper Sulfide Ores: Experiments With Sulfobacillus thermosulfidooxidans

“…Although the aluminum content appeared to provide a suitable environment for bacterial growth as the bacterial counts reached 10 6 cells/mL before the first bleeding, the solution potential only increased after the 41st day. This lag phase was longer than that observed in the columns operating at 30°C (Rodrigues, 2013). After the bleeding, the aluminum concentration (2–3 g/L) became larger than that of fluoride (1 g/L) and with the production of ferric iron fluoride toxicity was reduced even further enabling the Eh to increase.…”

Adaptation and Continuous Cultivation of Microorganisms Used in the Bioleaching of Sulphide Minerals: A Biotechnological Approach

“…They preferentially grow in acidic environments (i.e., they are acidophilic), and can even grow at pH close to zero (OTTOBONI & SATO, 2000), and such processes occur through the action of bacteria such as Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, and Acidithiobacillus thiooxidans etc. (BRIERLEY, 2010;RODRIGUES, 2015;TAO & DONGWEI, 2014;WATLING, 2006). According to Oliveira (2009), due to physiological and environmental similarities, these bacteria coexist simultaneously, intensifying the solubilization of the constituent metals of sulphide minerals, and are classified as chemoautotrophic, since they obtain energy from the oxidation of inorganic compounds such as sulphides (ALMEIDA, 2005;SILVAS, 2010), using CO 2 as the only carbon source for biomass production and are classified according to the temperature at which they develop, distinguishing themselves into: mesophiles (up to ~40 o C), moderate thermophiles (~40 -~55 o C) and extreme thermophiles (~55 -~80 o C) (CHANG et al, 2000;NAGPAL et al, 2000).…”