Chronic impact of tetracycline on nitrification kinetics and the activity of enriched nitrifying microbial culture

Tugce Katipoglu-Yazan*, Christophe Merlin, Marie Noëlle Pons, Emine Ubay-Cokgor, Derin Orhon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)

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 100mg COD/L of peptone mixture and 50mgN/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 50mg/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.

Original languageEnglish
Pages (from-to)227-238
Number of pages12
JournalWater Research
Volume72
DOIs
Publication statusPublished - 1 Apr 2015

Bibliographical note

Publisher Copyright:
© 2014 Elsevier Ltd.

Funding

This study was conducted as a part of the project Evaluation of the Biodegradation Characteristics and Toxicity/Inhibition Effects of Selected Antibiotics on Nitrification Systems and supported by joint doctoral degree program of Turkish Academy of Sciences and Scientific Research Fund of Istanbul Technical University. The authors would like to thank Dr. Xavier Bellanger and Hélène Guilloteau for their advice, assistance, and support throughout qPCR and cloning experiments.

FundersFunder number
Istanbul Teknik Üniversitesi

    Keywords

    • Enriched microbial culture
    • Gene activity
    • Modeling
    • Nitrification
    • Respirometry

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