title: Inhibition and biotransformation potential of veterinary ionophore antibiotics under different redox conditions.
abstract: Veterinary ionophore antibiotics (IPAs) are polyether compounds used extensively in the livestock industry to promote animal growth and prevent coccidia infection. However, the environmental fate and impact of IPAs are not fully understood. In this study, the inhibition and biotransformation potential of the most commonly used IPAs, monensin (MON) and salinomycin (SAL), were investigated under well-defined aerobic, nitrate-reducing, fermentative/sulfate-reducing, and fermentative/methanogenic conditions. Batch assays were conducted with mixed cultures developed from poultry litter (PL), PL-fertilized soil, and municipal anaerobic sludge. Significant transformation of MON and SAL was observed in aerobic, low-buffer capacity culture series as a result of abiotic acid-catalyzed IPAs hydrolysis induced by nitrification. Biotransformation of IPAs was the main transformation process in aerobic, high-buffer capacity culture series. MON persisted under fermentative/sulfate-reducing conditions, whereas SAL was transformed by fermentative bacteria. Both MON and SAL were stable under nitrate-reducing and methanogenic conditions. At IPAs concentrations up to 1 mg/L, MON inhibited only methanogenesis, whereas SAL did not impact any of the biological processes investigated in this study. Multiple, new primary IPA biotransformation products were observed on LC/MS, and their molecular structures were tentatively identified by analyzing LC/MS/MS fragmentation patterns. Overall, MON and SAL exhibited different inhibition and biotransformation patterns at each redox condition tested, which could greatly influence their fate and impact upon their release into the environment as a result of agricultural activities.
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
authors.forename: Peizhe
authors.initials: P
authors.lastname: Sun
authors.forename: Ching-Hua
authors.initials: CH
authors.lastname: Huang
authors.forename: Spyros G
authors.initials: SG
authors.lastname: Pavlostathis
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism; D001711:Biotransformation; D004777:Environment; D005285:Fermentation; D007476:Ionophores / Q000737:chemistry / Q000378:metabolism*; D008697:Methane / Q000378:metabolism; D008985:Monensin / Q000737:chemistry / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D011200:Poultry; D011714:Pyrans / Q000737:chemistry / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D013997:Time Factors; D019155:Veterinary Drugs / Q000737:chemistry / Q000378:metabolism*; D014866:Waste Products; D000095662:Polyether Polyketides
chemical_list: D000900:Anti-Bacterial Agents; D007476:Ionophores; D008697:Methane; D008985:Monensin; D009566:Nitrates; D011714:Pyrans; D013431:Sulfates; D019155:Veterinary Drugs; D014866:Waste Products; C010327:salinomycin; D000095662:Polyether Polyketides