ALTERAÇÕES MICROBIANAS EM ROCHAS: SOLUBILIZAÇÃO DO FERRO POR AÇÃO DE FUNGOS EM DIABÁSIOS

REGINA MARIA RIBEIRO, ADELAIDE MUSSI SANTOS, HEBE LABARTHE MARTELLI

Resumo


Experimental attack on a mafic rock by a liquid culture of an Aspergillus niger strain isolated from soil, which exhibited a striking solubilizing action upon its iron-containing minerals, was investigated. After 25 days, the iron content of the fungal solutions was 26 times higher than in the sterile control flasks. The microbiological activity was followed by the dry weight of the mycelium, the glucose consumption, the evolution of the total acidity, and the pH value of the cultures. The kinetics of the iron solubilization of the mycelial growth and the metabolic activity showed significant relationships. The mycelial growth was improved by the presence of the cations extracted from the rock samples. The solubility of iron in these minerals depended on their nature, the surface of attack, and the concentration of the metabolic products; probably all three. Formation of complex could be the mechanism involved, considering that a strong cation exchange-resin was not able to extract iron from the culture solutions.


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