Avaliação da capacidade de remoção de cr (vi) por microrganismos isolados de solo contaminado

Abstract

Effluents containing toxic metals in high concentrations, when improperly disposed of, represent a serious problem for the environment. Hexavalent chromium (Cr VI) is a highly toxic metal and carcinogenic to living organisms. This heavy metal is used in industries from different segments and is therefore found at high concentrations in industrial effluents. In this way, this work had the intention of proposing an economically viable alternative for the treatment of Cr (VI) contaminated effluent, since the most used conventional treatments (physical and chemical) present high costs and generate high byproducts. In this context, biological treatment through the removal of Cr (VI) by microorganisms, is a potentially attractive technology. Thus, the objective of the study was to isolate, select, identify and evaluate the potential of fungal strains for the removal of Cr (VI) from aqueous solutions, aiming at subsequent bioremediation of Cr (VI) contaminated effluents. Seven fungal strains were isolated from the contaminated soil, which were submitted to Cr (VI) tolerance tests by Minimum Inhibitory Concentration (MIC). Two isolated microorganisms (MOA and MOF) presented MICs for Cr (VI) above 700 mg.L-1. The strains belonged to the genus Cladosporium sp. as concluded based on studies of genetic profile. The two fungal strains were submitted to tests to evaluate Cr (VI) removal of synthetic effluent containing different concentrations of Cr (VI). The maximum Cr (VI) removal was 100%, obtained in 96 hours, by fermentation with the MOA inoculated in a synthetic effluent with initial Cr (VI) concentration of 20 mg.L-1. Therefore, this study reveals the strong potential of fungi of the genus Cladosporium sp. for the removal of Cr (VI) from industrial effluents.