Bacterial Degradation of Ibuprofen: Insights into Metabolites, Enzymes, and Environmental Fate Biodegradation of Ibuprofen by Achromobacter Species

In recent years, pharmaceuticals have emerged as pollutants due to their incomplete degradation in sewage treatment plants and their ability to cause physiological problems in humans even at low doses. Understanding the environmental fate of pharmaceutical pollutants and the mechanisms involved in their degradation is crucial for developing strategies to mitigate their impact on ecosystems and human health. In this study, the degradation of pharmaceutical compound ibuprofen was achieved by employing two bacterial strains, Achromobacter spanius strain S11 and Achromobacter piechaudii S18, previously isolated from contaminated water. These strains were capable of degrading ibuprofen as their sole carbon source. The study aimed to identify intermediate metabolites, determine the enzymes involved, and detect specific genes related to ibuprofen degradation. Different concentrations of ibuprofen, temperatures, and pH levels were tested. Both A. spanius S11 and A. piechaudii S18 successfully degraded ibuprofen. A. spanius S11 showed a degradation efficiency of 91.18% after only 72 h and reached 95.7% after 144 h, while A. piechaudii S18 exhibited degradation efficiencies of 72.39% and 73.01% after three and seven days, respectively. The LC-MS technique was used to identify biodegradation metabolites produced by A. spanius S11. The results indicated that the first step was hydroxylation followed by oxidation via the combination of monooxygenases that catalyze the C-H hydroxylation and dehydrogenases. Furthermore, the detection of intermediate metabolites of trihydroxyibuprofen suggested that the biodegradation of ibuprofen by A. spanius S11 can occur through multiple mechanisms. The highest enzyme activities were recorded for catechol 1,2-dioxygenase, 4.230 ± 0.026 U/mg, followed by laccase, 2.001 ± 0.215 U/mg. This study demonstrates the potential of Achromobacter strains, particularly A. spanius (S11), in degrading ibuprofen. These findings provide insights into the ibuprofen degradation process, intermediate metabolites, and relevant genes.