Master Thesis - Anoxic microbial transformation of antibiotics

The Helmholtz Centre for Environmental Research (UFZ) with its 1,100 employees has gained an excellent reputation as an international competence centre for environmental sciences. We are part of the largest scientific organisation in Germany, the Helmholtz association. Our mission: Our research seeks to find a balance between social development and the long-term protection of our natural resources.

The group “Anoxic transformation” in the Department of Environmental Biotechnology is offering a master thesis for six months in “Anoxic microbial transformation of antibiotics”. The global overconsumption of antibiotics, their persistency in wastewater and occurrence in the environment lead to the propagation of antibiotic resistant bacteria and antibiotic resistance genes. Sulfonamide antibiotics (SAs) in combination with the antibiotic trimethoprim are one of the most prescribed antibiotics in livestock farming and are frequently detected in various environmental compartments. Due to the incapability of aerobic techniques to sufficiently remove SAs from wastewater, researchers focused on anaerobic techniques emphasizing the suitability of sulfate-reducing bacteria (SRB) to transform SAs. However, the knowledge in regard to the molecular process of SA transformation by SRBs and the role of their reductive transformation in the sulfate reducing metabolism is limited to only a few studies. The extent to which SRBs can transform sulfonamides and chemically similar antibiotics, also under reduction of other electron acceptors is not elucidated yet. The following specific objectives are supposed to be investigated within the master thesis: A) investigate the anaerobic transformation of other SAs and trimethoprim than SMX and their metabolites by pure strains of sulfate-reducing bacteria; B) test the capability of SRBs to reductively transform isoxazole moiety- containing antibiotics other than SMX; C) test the capability of SRBs to reductively transform SAs while respiring alternative terminal electron acceptors then sulfate. Overall, the described work will enhance the understanding of relevant natural attenuation processes of SAs, trimethoprim and other antibiotics in the environment. It will help to elucidate the favourable conditions and proposes responsible organisms ideally rendering these concerning micropollutants less recalcitrant and consequently reducing the risk of antibiotic resistance propagation in the environment.