Organohalide-respiring Deltaproteobacteria

Organohalide respiration was first discovered in the deltaproteobacterium Desulfomonile tiedjei, which used 3-chlorobenzoate as the respiratory electron acceptor. Since this breakthrough discovery, the organohalide-respiring phenotype was demonstrated in 6 out of the 21 currently published families of the class Deltaproteobacteria. A survey of 208 available deltaproteobacterial genome sequences identified putative reductive dehalogenase genes in about 10 % of the genomes, suggesting that the ability to perform reductive dechlorination is not rare among the Deltaproteobacteria. For example, free-living Geobacter lovleyi strains dechlorinate the priority pollutants tetrachloroethene and trichloroethene in freshwater aquifers whereas the sponge-associated species Desulfoluna spongiiphila uses bromo- and iodophenols as electron acceptors in marine environments. Organohalide-respiring Deltaproteobacteria inhabit diverse habitats where they fulfill key functions in the global cycling of halogens, and have relevant roles in bioremediation applications.