Acute impact of erythromycin on substrate utilization by activated sludge: Effect of sludge age

Ilke Pala-Ozkok*, Emine Ubay-Cokgor, Zeynep Petek Cakar, Derin Orhon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


BACKGROUND: This study involved model evaluation of the acute impact of erythromycin on substrate utilization of aerobic activated sludge biomass, at sludge ages of 10 and 2days. Acute inhibition experiments involved two fill/draw reactors, supplying the biomass, and two sets of batch reactors, which were all fed with the same peptone-meat extract mixture. Each set included a control reactor started without antibiotic addition and parallel reactors with pulse erythromycin additions. RESULTS: Model evaluation of the oxygen uptake rate, chemical oxygen demand and intracellular storage profiles indicated that erythromycin did not affect microbial growth. However, it totally stopped substrate storage and accelerated endogenous respiration. Enhanced endogenous respiration could be explained by higher maintenance energy required for generating specific inactivating enzymes to prevent the toxic effects of erythromycin. CONCLUSION: Major impact was partial obstruction/binding of available substrate for microbial utilization, suggesting uncompetitive inhibition. The present study is unique in emphasizing the increase in maintenance-energy requirements of microbial cultures upon erythromycin exposure, by respirometric and modeling approaches.

Original languageEnglish
Pages (from-to)1091-1102
Number of pages12
JournalJournal of Chemical Technology and Biotechnology
Issue number7
Publication statusPublished - Jul 2014


  • Activated sludge
  • Degradation
  • Kinetics
  • Modelling
  • Pharmaceuticals


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