title: Chronic impact of tetracycline on the biodegradation of an organic substrate mixture under anaerobic conditions.
abstract: The study evaluates the chronic impact of the antibiotic tetracycline on the biodegradation of organic substrate under anaerobic conditions. The experiments involved an anaerobic sequencing batch reactor fed with a synthetic substrate mixture including glucose, starch and volatile fatty acids, and operated in a sequence of different phases with gradually increasing tetracycline doses of 1.65-8.5 mg/L, for more than five months. Tetracycline exerted a terminal/lethal effect at 8.5 mg/L on the microbial community under anaerobic conditions, which caused the inhibition of substrate/COD utilization and biogas generation and leading to a total collapse of the reactor. The microbial activity could not be recovered and re-started within a period of more than 10 days, even after stopping tetracycline dosing. At lower doses, substrate utilization was not affected but a reduction of 10-20% was observed in the biogas/methane generation, suggesting that substrate utilization of tetracycline to the biomass was limiting their bioavailability. During the experiments, tetracycline was partially removed either through biodegradation or conversion into its by-products. The adverse long-term impact was quite variable for fermenting heterotrophic and methanogenic fractions of the microbial community based on changes inflicted on the composition of remaining/residual organic substrate.
authors.affiliation: Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey. cetecioglu@itu.edu.tr
authors.forename: Z
authors.initials: Z
authors.lastname: Cetecioglu
authors.forename: B
authors.initials: B
authors.lastname: Ince
authors.forename: M
authors.initials: M
authors.lastname: Gros
authors.forename: S
authors.initials: S
authors.lastname: Rodriguez-Mozaz
authors.forename: D
authors.initials: D
authors.lastname: Barceló
authors.forename: D
authors.initials: D
authors.lastname: Orhon
authors.forename: O
authors.initials: O
authors.lastname: Ince
mesh_terms: D000693:Anaerobiosis / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D001673:Biodegradation, Environmental / Q000187:drug effects; D056804:Biofuels / Q000032:analysis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology; D002245:Carbon Dioxide / Q000032:analysis; D005232:Fatty Acids, Volatile / Q000032:analysis; D008697:Methane / Q000032:analysis; D009930:Organic Chemicals / Q000302:isolation & purification*; D013752:Tetracycline / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D056804:Biofuels; D005232:Fatty Acids, Volatile; D009930:Organic Chemicals; D002245:Carbon Dioxide; D013752:Tetracycline; D008697:Methane