Wastewater-based epidemiology (WBE) employs the analysis of wastewater to detect and quantify drug use and discharge within a community. In this work, transformation products (TP) by microbes in the environment were identified after incubations in wastewater and an isolated microbial strain. The microbial strain was isolated from an enrichment culture of wastewater supplemented with 3,4-methylenedioxy-pyrovalerone, and identified by matrix assisted laser desorption - time of flight mass spectrometry as Pseudomonas putida (P. putida). Five pyrrolidinophenone-type psychoactive substances (PPPS) were then incubated in wastewater and in P. putida tryptic soy broth (TSB) growth cultures. TPs were identified using liquid chromatography coupled to mass spectrometry techniques. All TPs observed in P. putida TSB growth cultures were also identified in wastewater incubations. The main TP for all PPPSs in P. putida TSB growth cultures, and two PPPSs incubated in wastewater, were the N-desalkyl-carboxy-TPs. The study showed P. putida TSB growth cultures used for identification of TPs in wastewater, represent parts of the microbial community. With data provided in this type of experiments more information will be available to select targets for monitoring drug use by WBE. Copyright © 2017 John Wiley & Sons, Ltd.