Degradation of dioxinas and furanos policlorados for ligninolíticos basidiomecetos fungos and its application in biorremediação process. / Degradação de dioxinas e furanos policlorados por fungos basidiomicetos ligninoliticos e sua aplicação em processo de biorremediação.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are compounds produced as by-products, unintentionally, in industrials processes and combustion processes. Municipal solid waste incineration is one major source these compounds. The isomers with chlorines substituted in the 2,3,7,8 positions are thought to cause risks to human health due to their toxicity, carcinogenic potency, potential effects on animal reproductive and immunological systems and endocrine disrupting. PCDD/Fs are chemically stable, have low solubility in water, and have been shown to accumulate in the food chain. Public health risk from environmental exposure to dioxins from contaminated sites can be significant. As a result, the clean up of environmental dioxin contamination deserves more attention. Microbiological techniques are useful tools for the decontamination of toxic materials, which not only save energy but also reduce the need for additional chemicals. In this work twenty one basidiomycete fungal strains were evaluated and seven were pre-selected for their ability to grow in medium containing municipal wastes fly ashes contaminated with PCDD/Fs (62 ng I- TEQ/kg). All the seven strains produced ligninolytic enzymes and biosurfactants. Pleurotus sp CCB068 was selected among these seven strains due to high levels of the ligninolytic enzymes MnP (±19U/L) and laccase (±17 U/L) activities and of biosurfactants produced, as well as the reduction on the toxicity following its grow on the fly ashes containing medium. Pleurotus sp CCB068 was than used in experiments for the determination of its capacity to degrade dibenzofuran and PCDD/Fs. When grown on medium containing varied concentrations of fly ashes (50g/L; 70g/L; 90g/L; 130g/L; 170g/L, 210g/L and 250g/L), it was observed that 70 g/L medium favored the production of MnP and laccase by Pleurotus sp. CCB068 and reduction of the toxicity. Higher amounts of fly ashes inhibited both enzymes activities and toxicity reduction. Pleurotus sp. CCB068 degraded up to 74% of the tested compounds following its growth for 21 days, and was able to degrade 14 among the 17 PCDD/Fs isomers used. These results indicate that this strain has great potential for application in bioremediation of contaminated sites. Furthermore, heavy metals determination showed that Pleurotus sp CCB068 removed 100% of cadmium, 47 % of cromium, and 15.7 % of the lead present in the fly ashes used.

ASSUNTO(S)

furanos toxicologia dioxinas biorremediação toxicidade - testes

ACESSO AO ARTIGO

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