The effect of cadmium on the kinetics of trichloroethylene biodegradation by Pseudomonas (burkolderia) picketti PK01 under denitrifying conditions

Pollution resulting from leaking and failing landfills is of concern to public health due to contamination of community drinking water. Chlorinated aliphatic hydrocarbons such as trichloroethylene (TCE) are common to both municipal and hazardous waste landfills and are potential contaminants of groundwater. Landfill leachate typically contains large amounts of organic carbon, nitrogen, and heavy metals and possesses a low redox potential. The kinetics of TCE degradation using a toluene oxidizing bacteria Pseudomonas (Burkholderia) picketti PK01under nitrate reducing conditions was determined both in the presence and absence of the common landfill contaminant cadmium. A first order rate law was found to describe TCE degradation by Pseudomonas (Burkholderia) picketti PK01 over the TCE concentration range investigated. The rate constant for TCE degradation under denitrifying conditions in the absence of cadmium was 2.1×10−4 ml/μg protein/h. The rate constant for TCE degradation in the presence of 5 ppm cadmium was determined to be 6.5×10−5 ml/μg protein/h; representing a sixty nine percent decrease in the rate constant. Significant TCE degradation occurred over the course of the experiments. Results indicate that the presence of 5 ppm of cadmium had the effect of decreasing the TCE degradation activity of the microorganism Burkholderia picketti PK01. Implications for remediation and prediction of biodegradation of TCE in landfill impacted groundwater is discussed.