Genomic insights into organohalide respiration

Novel Firmicutes Group Implicated in the Dechlorination of Two Chlorinated Xanthones, Analogues of Natural Organochlorines

“…Indeed, recently a Shewanella sediminis strain was found to contain five putative reductive dehalogenases, one of which was confirmed to be functional in the dechlorination of tetrachloroethene, despite the fact that the genus has never been associated with organohalide respiration (50). Isolates of the genera Dehalococcoides, Dehalogenimonas, "Dehalobium," Dehalobacter, Desulfitobacterium, Anaeromyxobacter, Geobacter, Desulfomonile, Desulfuromonas, Desulfovibrio, Sulfurospirillum, Propionibacterium, Clostridium, and Desulfoluna have been linked to the specific dechlorination activities of several compounds (51,52,53,54), yet dechlorination unattributable to any of these genera has also been frequently observed (23,30,46,55). Our results implicate a group within the Firmicutes, the Gopher group, in the dechlorination of 2,7-dichloroxanthone and 5,7-dichloro-1,3-dihydroxylxanthone and point to the need for additional research on the biodiversity of organohalide respirers.…”

Exploiting the intrinsic microbial degradative potential for field-based in situ dechlorination of trichloroethene contaminated groundwater

“…Chlorine atoms on the contaminant can be decoupled by various mechanisms such as hydrolysis, dehydrochlorination, hydrogenolysis and dichloroelimination [4]. Biological methods or bioremediation can also be effectively used for treating TCE with reductive dechlorination being largely facilitated by microbial dehalogenases such as PceA, TceA, VcrA and BvcA enzymes [5]. Although the use of any of these methods depends upon economical, legislative and site-specific technical factors, biological approaches are sometimes preferred due to their cost effectiveness and environmental friendly way of reductive dechlorination.…”

Reductive Dehalogenases Come of Age in Biological Destruction of Organohalides

“…separate two-electron transfer mechanisms (i.e., /-and b-elimination). An /-elimination results in the exchange of a halogen substituent with a proton, while a b-elimination involves the simultaneous removal of two adjacent halogen substituents resulting in an unsaturated product (Equation 1A, B, modified from [7]). ORB mainly belong to three bacterial phyla (Chloroflexi, Firmicutes, and Proteobacteria), and are capable of utilizing various halogenated organic substrates as their terminal electron acceptors via their reductive dehalogenation system.…”