Biodegradation of Technical Products of Brominated Flame Retardant by Fungi

This chapter examines the degradation by the white-rot fungus Trametes versicolor of three commercial polybrominated diphenyl ether (PBDE) mixtures that have been used more in industry, and consequently, they are detected with great frequency in the environment. PBDEs are a group of compounds that are used in several products as flame retardants and they are highly recalcitrant to their degradation in the environment. The three products selected to study their degradation by the fungus in liquid media correspond to decabromodiphenyl ether (deca-BDE), octabromodiphenyl ether (octa-BDE) and pentabromodiphenyl ether (penta-BDE) mixtures. T. versicolor is able to degrade the three different PBDE commercial mixtures in aqueous media obtaining high final removal efficiencies. The degradation products obtained from the treatment by the fungus correspond to some hydroxylated PBDEs with different degrees of bromination, which suggests that the degradation consists of a hydroxylation enzymatic reaction. In addition, the intracellular enzyme cytochrome P450 is implicated in the first step of deca-BDE degradation by T. versicolor. However, the toxicity tests showed that toxicity in the aqueous media increases after the treatment by the fungus. On the other hand, this chapter reviews the biological treatments in aerobic and anaerobic conditions developed until present to remove PBDEs from aqueous media and soil or sewage sludge.