An investigation of the ability of Pseudomonas fluorescens to degrade the antidepressent sertraline (Zoloft¨)

Brad Palanski, The College of Wooster


Pharmaceuticals are now a well-recognized class of environmental contaminants that have been shown to elicit severe negative effects on aquatic life at environmentally relevant concentrations. Sertraline (Zoloft®), a selective serotonin reuptake inhibitor, is an antidepressant with documented ecotoxic effects that is ubiquitous in aquatic environments near wastewater treatment plants (WWTPs). However, little is known about the breakdown of sertraline in WWTPs and the environment. Recent studies suggested that a bacterium (Pseudomonas fluorescens) isolated from the Wooster WWTP was capable of metabolizing sertraline and tentatively identified norsertraline (N-desmethylsertraline) as a metabolite. The aim of this study was to further investigate this proposed metabolism. An improved method for the detection of norsertraline and other metabolites by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed, and computational methods were used to predict a possible pathway of bacterial sertraline metabolism. LC-MS/MS analysis of the supernatants of bacterial liquid cultures grown in the presence of sertraline showed that the concentration of sertraline decreased during log-phase growth; however, no norsertraline or other metabolites were identified. A subsequent control experiment indicated that the physical partitioning of sertraline to cell biomass was significant, providing an explanation for the decrease in sertraline concentration in the absence of any metabolites. Although this study showed that Pseudomonas fluorescens does not metabolize sertraline, the LC-MS/MS method and the computationally predicted pathway of sertraline breakdown provide a starting point for future investigations on sertraline biodegradation. Such studies are needed to allow a comprehensive assessment of the combined ecotoxicity of sertraline and its degredation products. Additionally, knowledge of pathways involved in sertraline breakdown could lead to novel methods for the remediation of sertraline within WWTPs.


© Copyright 2011 Brad Palanski