Enhanced remediation of soil contaminated with selected non-steroidal anti-inflammatory drugs by the bioaugmentation with newly isolated strain Serratia marcescens MC-2/23

Abstract

Excessive use of non-steroidal anti-inflammatory drugs (NSAIDs) has resulted in environmental pollution, including soil contamination. Hence, various methods are required to remove these pollutants. One such approach is bioaugmentation, which involves introducing microorganisms capable of degrading organic contaminants into different environmental matrices. The novelty of this work relates to the isolation of a new bacterial strain Serratia marcescens MC-2/23, from raw sewage, capable of degrading the most commonly used NSAIDs, i.e. ibuprofen, diclofenac, and naproxen. Moreover, this is the first study wherein bioaugmentation with bacteria has been used for the degradation of NSAIDs in soil. Experiments using a mineral medium supplemented with individual drugs revealed that the MC-2/23 strain utilizes these compounds as carbon and energy sources. The highest degradation rates were observed for ibuprofen and naproxen, with DT50 values of 3.5 and 3.0 days, respectively. Additionally, introducing the MC-2/23 strain into sterile soil confirmed its ability to degrade these drugs. When applied to soil contaminated with the target NSAIDs, the MC-2/23 strain reduced the DT50 values of ibuprofen, diclofenac, and naproxen by 13-, 3.1-, and 4-fold, respectively, compared to the soil with natural microflora. These findings suggest that this strain could be effective for the bioremediation of NSAID-contaminated soils. However, the molecular and biochemical aspects of NSAID degradation need to be investigated in depth to elucidate the underlying pathways and accurately assess the survival and competitiveness of the MC-2/23 strain with native microflora to understand its interaction with the soil environment before it can be used in large-scale bioremediation.