"Dehalobium chlorocoercia" DF-1-from discovery to application

Abstract

"Dehalobium chlorocoercia" strain DF-1 is an organohalide respiring ultramicrobacterium isolated from a tidal estuary of Charleston Harbor using a polychlorinated biphenyl (PCB) congener as the sole electron acceptor. Organohalide respiration occurs by dechlorination of PCB congeners with doubly flanked chlorines, but this strain is also capable of dechlorinating chlorobenzenes with doubly flanked chlorines and tetra- and tri-chloroethene to a mixture of cis- and trans-1,2-dichloroethene. The range of PCB congeners dechlorinated from an Aroclor is limited in comparison with other PCB respiring strains; however, "D. chlorocoercia" strain DF-1 is capable of dechlorinating PCBs at environmentally relevant concentrations that are typically below saturation in water. In sediment-free medium an unidentified water-soluble factor from a Desulfovibrio sp. is required for growth. "D. chlorocoercia" strain DF-1 is osmotolerant, enabling it to grow and dechlorinate PCBs in sediments ranging from freshwater to marine. What follows is a description of "D. chlorocoercia" strain DF-1 and some of its related PCB respiring species from the perspective of environmental detection, dechlorination pathways and kinetics, biostimulation, electrostimulation, and finally bioaugmentation to enhance PCB degradation in sediments.