N1: Degradation of recalcitrant organic trace pollutants in biofilms at solid-water interfaces

Doctoral student: Marcella Nega

Supervisors: Prof. Dr. Ulrich Szewzyk, Dr. Burga Braun, Dr. Peter Casper, Prof. Dr. Mark Gessner

Introduction

Organic trace pollutants are regularly found and detectable in urban surface waters. Aquatic environments are impacted by these organic compounds, including pharmaceuticals, and concern exists about their presence and the influence they exert on biological activities. This scenario mainly occurs because pharmaceuticals are difficult to be removed during wastewater treatment. Therefore, these compounds reach surface waters in unchanged forms, and some as metabolites. The degradation of pharmaceuticals in various habitats have been demonstrated and discussed in several studies (De Weert et al., 2010; Kümmerer, 2010; Benotti and Brownawell, 2009; Kunkel & Radtke, 2008; Groning et al., 2007). But there is still lack of knowledge about the rates and mechanisms of microorganisms in the degradation of pharmaceuticals.

Aims

One of the aims in this project is to study the potential of iron/manganese depositing bacteria (IMDB) to degrade (recalcitrant) pollutants such as diclofenac, carbamazepine and iodinated contrast media in defined laboratory experiments. After the screening for potential organisms that can degrade these compounds, we focus on the identification of transformation products that are produced. Identification of such compounds will provide us with information about the degradation pathways and products that could be produced by different strains. In the long-run we want to identify genes that are up-regulated during degradation processes and we want to quantify different enzymes activities.  Furthermore we want to address if there is an impact of the discharge of a wastewater treatment plant on the patterns of microbial communities. With Next-generation sequencing technique we will investigate the composition of the microbial communities up- and downstream of the WWTP discharge in sediments and we will correlate it with micropollutant concentrations (polar acidic pharmaceuticals) and physico-chemical parameters to see if we can find evidence for an impact on the microbial communities.

Results

The screening for potential iron/manganese depositing bacteria showed that diclofenac disappeared with active bacteria but not with dead bacteria. Further the results showed evidence for biotic removal of diclofenac in microbial degradation assays.

Collaborations

• UWI Projects: T6 on the deiodination of iodinated contrast media
• Common topics: Micropollutants, Biogeochemical processes
• Institutions: BWB, Chair of Water Quality Control (TU Berlin), Max Planck Institute For Evolutionary Biology in Plön

References

Benotti, M. J., & Brownawell, B. J. (2009). Microbial degradation of pharmaceuticals in estuarine and coastal seawater. Environmental Pollution, 157 (3), 994–1002

De Weert.J., Vinas,M., Grotenhuis,T., Rijnaarts,H. & Langenhoff,A. (2010): Aerobic nonylphenol degradation and nitro-nonylphenol formation by microbial cultures from sediments. Appl Microbiol Biotechnol 86:761-771

Groning,J., Held,C., Garten,C., Claussnitzer, U., Kaschabek, S.R. & Schlömann,M. (2007): Transformation of diclofenac by the indigenous microflora of river sediments and identification of a major intermediate. Chemosphere 69:509-516

Kümmerer, K. (2010). Pharmaceuticals in the environment. Molecular Biology, 6.

Kunkel,U., Radke,M. (2008): Biodegradation of acidic pharmaceuticals in bed sediments: insight from a laboratory experiment. Environ Sci Technol 42:7273-7279

Initial project plan