title: Chronic impact of tetracycline on nitrification kinetics and the activity of enriched nitrifying microbial culture.
abstract: This study evaluated the chronic impact of tetracycline on biomass with enriched nitrifying community sustained in a lab-scale activated sludge system. For this purpose, a fill and draw reactor fed with 100 mg COD/L of peptone mixture and 50 mg N/L of ammonia was sustained at a sludge age of 15 days. At steady-state, the reactor operation was continued with a daily tetracycline dosing of 50 mg/L for more than 40 days, with periodic monitoring of the microbial composition, the nitrifying bacteria abundance, as well as the amoA and 16S rRNA gene activity, using molecular techniques. Changes in the kinetics of nitrification were quantified by modelling concentration profiles of major nitrogen fractions and oxygen uptake rate profiles derived from parallel batch experiments. Activated sludge modeling results indicated inhibitory impact of tetracycline on the growth of nitrifiers with a significant increase of the half saturation coefficients in corresponding rate equations. Tetracycline also inactivated biomass components of the enriched culture at a gradually increasing rate with time of exposure, leading to total collapse of nitrification. Molecular analyses revealed significant changes in the composition of the microbial community throughout the observation period. They also showed that continuous exposure to tetracycline inflicted significant reduction in amoA mRNA and 16S rRNA levels directly affecting nitrification. The chronic impact was much more pronounced on the ammonia oxidizing bacteria (AOB) community. These observations explained the basis of numerical changes identified in the growth kinetics of nitrifiers under stress conditions.
authors.affiliation: Istanbul Technical University, Faculty of Civil Engineering, Environmental Engineering Department, 34469 Maslak, Istanbul, Turkey; Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564, CNRS, 15 Avenue du Charmois, 54500 Vandoeuvre-lès-Nancy, France. Electronic address: tugce.katipoglu@gmail.com.
authors.forename: Tugce
authors.initials: T
authors.lastname: Katipoglu-Yazan
authors.affiliation: Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), UMR 7564, CNRS, 15 Avenue du Charmois, 54500 Vandoeuvre-lès-Nancy, France. Electronic address: christophe.merlin@univ-lorraine.fr.
authors.forename: Christophe
authors.initials: C
authors.lastname: Merlin
authors.affiliation: Université de Lorraine, Laboratoire Réactions et Génie des Procédés, UMR 7274, CNRS, 1 rue Grandville, France. Electronic address: marie-noelle.pons@univ-lorraine.fr.
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Pons
authors.affiliation: Istanbul Technical University, Faculty of Civil Engineering, Environmental Engineering Department, 34469 Maslak, Istanbul, Turkey. Electronic address: ubay@itu.edu.tr.
authors.forename: Emine
authors.initials: E
authors.lastname: Ubay-Cokgor
authors.affiliation: Istanbul Technical University, Faculty of Civil Engineering, Environmental Engineering Department, 34469 Maslak, Istanbul, Turkey; ENVIS Energy and Environmental Systems R&D Ltd, İTU Arı Teknokent, Arı 1 Building No.16, Maslak 34469, Turkey. Electronic address: orhon@itu.edu.tr.
authors.forename: Derin
authors.initials: D
authors.lastname: Orhon
mesh_terms: D001419:Bacteria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D061249:Batch Cell Culture Techniques; D002138:Calibration; D016000:Cluster Analysis; D003198:Computer Simulation; D007700:Kinetics; D008962:Models, Theoretical; D058465:Nitrification / Q000187:drug effects*; D010100:Oxygen / Q000378:metabolism; D013752:Tetracycline / Q000494:pharmacology*
chemical_list: D013752:Tetracycline; D010100:Oxygen
keywords: Enriched microbial culture; Gene activity; Modeling; Nitrification; Respirometry