Removal of diclofenac by environmental bacteria in planktonic and immobilized systems using microfluidic devices

Abstract

Diclofenac, a widely used non-steroidal anti-inflammatory drug, is a persistent pharmaceutical contaminantfrequently detected in aquatic environments. Its incomplete removal by conventional wastewater treatmentplants highlights the urgent need for alternative, sustainable bioremediation strategies. In this study, six environmentalbacterial strains (Rhodococcus jostii 016, Rhodococcus erythropolis 20, Bacillus sp. B18, Rhodococcus sp.F27, Kocuria sp. H19, and Pseudomonas sp. P26) were evaluated for their tolerance to different diclofenac concentrationsand their removal capacity in planktonic cultures supplemented with 1 mg/L diclofenac. All strainsexhibited tolerance to diclofenac concentrations up to 100 mg/L and achieved removal efficiencies between21.22% and 34.93% in glucose-supplemented medium. Among three pre-selected strains evaluated for biofilmformation as a cell immobilization strategy, Pseudomonas sp. P26 showed the strongest biofilm-forming abilityand was selected for further kinetic and microfluidic removal studies. Under planktonic conditions, Pseudomonassp. P26 achieved 18.5% diclofenac removal after five days, whereas biofilms formed within microfluidic devicesdisplayed a markedly higher efficiency, reaching 98.5% removal within 24 h. These findings demonstrate thepotential of Pseudomonas sp. P26 biofilms cultivated in microfluidic systems for diclofenac removal, highlightingtheir relevance as a promising approach for further investigation and potential application in the treatment ofthis persistent emerging contaminant.