Removal of Ibuprofen in Water by Bioaugmentation with Labrys neptuniae CSW11 Isolated from Sewage Sludge—Assessment of Biodegradation Pathway Based on Metabolite Formation and Genomic Analysis

Ibuprofen (IBP) is one of the most consumed drugs in the world. It is only partially removed in wastewater treatment plants (WWTPs), being present in effluent wastewater and sewage sludge, causing the widespread introduction of IBP as an emergent xenobiotic in different environmental compartments. This study describes the use of <i>Labrys neptuniae</i> CSW11, recently described as an IBP degrader, through bioaugmentation processes for the removal of IBP from water under different conditions (additional carbon sources, various concentrations of glucose and IBP). <i>L. neptuniae</i> CSW11 showed very good results in a wide range of IBP concentrations, with 100% removal in only 4 days for 1 and 5 mg L^-1 IBP and 7 days for 10 mg L^-1, and up to 48.4% removal in 28 days for IBP 100 mg L^-1 when using glucose 3 g L^-1 as an additional carbon source. Three IBP metabolites were identified during the biotransformation process: 1-hydroxyibuprofen (1-OH-IBP), 2-hydroxyibuprofen (2-OH-IBP), and carboxyibuprofen (CBX-IBP), whose concentrations declined drastically in the presence of glucose. IBP metabolites maintained a certain degree of toxicity in solution, even when IBP was completely removed. The results indicate that <i>L. neptuniae</i> CSW11 can be quite effective in degrading IBP in water, but the bioaugmentation method should be improved using CSW11 in consortia with other bacterial strains able to degrade the toxic metabolites produced. A genome-based analysis of <i>L. neptuniae</i> CSW11 revealed different enzymes that could be involved in IBP biodegradation, and a potential metabolic pathway was proposed based on the metabolites observed and genome analysis.