Microbial Degradation of Contaminants of Emerging Concern by Pseudomonas putida in Wastewater Treatment Plants

Contaminants of Emerging Concern (CECs) are a class of contaminants that are commonly found in urban wastewater treatment plants (WWTP) at low concentrations. These compounds include antibiotic drugs, personal care products, and industrial chemicals, which are widely used in modern society. Although they provide undeniable benefits in our daily lives, their accumulation in the environment poses a significant risk to human health and the ecosystem. Due to the incomplete removal of these compounds by traditional WWTPs, there is a need to understand the interactions between microbes and CECs to develop effective solutions to this environmental challenge. Pseudomonas putida is a bacterium commonly found in water-related habitats, including freshwater streams, forests, and WWTPs. It is known for its ability to degrade various organic compounds, making it a suitable model for understanding the linkages between bacterial enzymes and CECs found in WWTPs. In this study, isolated Pseudomonas putida strain KT2440 was cultured in lab-scale reactors to mimic the WWTP environment. The degradation of this isolated strain towards different groups of CECs were studied over a 24-hour period using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Mass spectrometry-based quantitative proteomics was also performed at different sampling points to establish a linkage between the enzyme expression profile of this strain and its degradation of CECs via bioinformatics analysis. The results of this study demonstrated that Pseudomonas putida KT2440 is capable of degrading atrazine, acetamiprid, carbendazim, diclofenac acid, erythromycin, and sulfamethazine at lab scale. At the 20-hour time point, the enzyme expression profile indicated a high protein abundance of various oxidoreductases that could explain the observed CEC degradation.The study's findings provide important insights into the potential of Pseudomonas putida as a bioremediation agent for CECs in WWTPs. The degradation of CECs by Pseudomonas putida KT2440 is a significant contribution to the bioremediation process, and its enzyme expression profile can serve as a case study for more complex interactions of microbes and CECs in real WWTPs. Furthermore, this study supports the potential of Pseudomonas putida as a promising strain for various bioremediation applications. Finally, this study's results can help develop more efficient and effective methods for removing CECs from wastewater, which can contribute to the protection of public health and the environment.