Three Methods of Cometabolism For In Situ Bioremediation

Cometabolism is considered the indirect beneficial destruction of a contaminant compound by a microorganism that is growing on another substrate. While the benefit may be fortuitous, cometabolism can be directed and controlled to improve the environmental benefit.

CL Solutions has used cometabolism in three ways for bioremediation of different types of compounds.

• CL-Out® is a consortium of microbes that cometabolize chlorinated solvents under aerobic to anoxic conditions. The microbes metabolize dextrose as a primary substrate and constituatively produce dioxygenase enzymes that convert PCE, TCE and other chlorinated aliphatic compounds into organic acids that are metabolized.

• CL-Out® has been used to remove perchlorate from soil and ground water while growing on a substrate and using perchlorate for respiration. The substrate provides a carbon source and the perchlorate reduced by respiration. This approach can also be used for denitrification.

• In a novel approach, a simple sugar can be used as a substrate to support microbial growth when the concentrations of the target contaminant are too low to support an effective population density. This approach was used for pesticide bioremediation when the ground water concentrations were less than 0.1 µg/L and the remediation goal was 0.002 µg/L.