Dioxins such as polychlorinated dibenzo-p-dioxins (PCDDs) are among the most toxic and carcinogenic environmental pollutants that can enter the food chain. There are currently few methods available to detoxify these chemicals, but one of the most promising is the use of microbial dioxin respiration pathways. In the January 23 Nature, Michael Bunge and colleagues at the Martin-Luther-Universität Halle-Wittenberg, Germany, describe an anaerobic bacterium capable of detoxification through reductive dehalogenation of chlorinated dioxins (Nature, 421:357-360, January 23, 2003).

Bunge et al. examined freshwater sediments from areas known to contain high levels of PCDD contamination. In four enrichment cultures they identified dioxin-dechlorinating Dehalococcoides species. In addition, they showed that the previously described chlorobenzene-dehalorespiring bacterium Dehalococcoides sp. strain CBDB1 is able to reductively dechlorinate selected dioxin congeners.

"Owing to their dehalogenation potential, indigenous and introduced organisms of the Dehalococcoides cluster are an important addition to the arsenal of...

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