Biodiversity of Dioxin-Degrading Microorganisms and Potential Utilization in Bioremediation.

Abstract

Dioxins are a group of chloroaromatic compounds known to be toxic and carcinogenic, and persistent environmental pollutants. How to remedy dioxin-polluted environments is one of the most challenging problems in environmental technology. From ecological and economical viewpoints, biological methods using particular microorganisms and microbial consortia capable of dioxin transformation and degradation have greater appeal than physicochemical methods in their application for environmental remediation. Large numbers of microorganisms capable of degrading dioxins and dioxin-like compounds have been isolated and characterized. Information about the biodiversity, ecophysiology and molecular biology of dioxin-degrading microorganisms has accumulated particularly during the past decade. There are three major modes of microbial degradation and transformation of dioxins; that is, oxidative degradation by aerobic bacteria containing aromatic hydrocarbon dioxygenases, reductive dechlorination by anaerobic microorganisms and fungal oxidation with cytochrome P-450, lignin peroxidases and laccases. This article overviews the current knowledge of microbial degradation and transformation of dioxins as well as the biodiversity of microorganisms involved. Strategies directed towards the bioremediation of dioxin-polluted environments are discussed.

Biotransformation of Polychlorinated Dioxins and Microbial Community Dynamics in Sediment Microcosms at Different Contamination Levels

“…These chloroaromatics possibly undergo microbial breakdown as well as physicochemical degradation in the environment, as a number of studies have demonstrated the existence of a wide variety of dioxintransforming microorganisms 23,56) . However, information about the effects of microbial activity on the fate and dynamics of dioxins in contaminated areas is still scanty.…”

“…In recent years, microbial reductive dechlorination of PCDD/Fs and PCBs has received intensive study, because this biological activity is not only possibly the initial step in the biotransformation of organohalorides in the environment but also has important implications for engineered bioremediation 1,23,43,56) . Microbial dechlorination of PCDD/ Fs has been demonstrated in studies of anaerobic microcosms using contaminated sediment and soil 2,[7][8][9]12,20,31,49,52) .…”

Characterization of bacterial community structure in bioremediation treatment of herbicide/dioxin contaminated soil at field trials

“…NhiÒu vi khuÈn thuéc líp nµy cã kh ¶ n¨ng sö dông 2,4-D, 2,4,5-T, dioxin vµ c¸c hîp chÊt t−¬ng tù [2,3]. KÕt qu ¶ trong ®ît kh ¶o s¸t nµy còng phï hîp víi mét sè ph¸t hiÖn cña c¸c t¸c gi ¶ kh¸c vÒ ®a d¹ng vi sinh vËt trong ®Êt nhiÔm chÊt diÖt cá [11] vµ polychlorinated biphenyl (d¹ng hîp chÊt cã cÊu tróc t−¬ng tù dioxin) [10].…”

Functional Expression of Three Rieske Non-Heme Iron Oxygenases Derived from Actinomycetes inRhodococcusSpecies for Investigation of Their Degradation Capabilities of Dibenzofuran and Chlorinated Dioxins

“…6,7) Chlorinated dioxins can be microbially degraded (for reviews, see refs. [8][9][10][11]. In general, degradation proceeds co-metabolically, and it is relatively slow for some congeners, especially of highly chlorinated dioxin.…”