Operating conditions influence microbial community structures, elimination of the antibiotic resistance genes and metabolites during anaerobic digestion of cow manure in the presence of oxytetracycline

• Published in: Ecotoxicology and environmental safety Vol. 147; pp. 349 - 356
• Main Authors: Turker, Gokhan, Akyol, Çağrı, Ince, Orhan, Aydin, Sevcan, Ince, Bahar
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-01-2018
• Subjects: Anaerobic digestion; Anaerobiosis; Animals; Anti-Bacterial Agents - metabolism; Anti-Bacterial Agents - toxicity; Antibiotic resistance gene; Biodegradation, Environmental; Bioreactors - microbiology; Cattle; Chromatography, High Pressure Liquid; Drug Resistance, Microbial - genetics; Female; Manure - analysis; Manure - microbiology; Metabolite; Microbial community; Microbial Consortia - drug effects; Microbial Consortia - genetics; Oxytetracycline; Oxytetracycline - metabolism; Oxytetracycline - toxicity; Real-Time Polymerase Chain Reaction; Tandem Mass Spectrometry; Oxytetracycline; Metabolite; Anaerobic digestion; Microbial community; Antibiotic resistance gene
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2017.08.044

The way that antibiotic residues in manure follow is one of the greatest concerns due to its potential negative impacts on microbial communities, the release of metabolites and antibiotic resistant genes (ARGs) into the nature and the loss of energy recovery in anaerobic digestion (AD) systems. This study evaluated the link between different operating conditions, the biodegradation of oxytetracycline (OTC) and the formation of its metabolites and ARGs in anaerobic digesters treating cow manure. Microbial communities and ARGs were determined through the use of quantitative real-time PCR. The biodegradation of OTC and occurrence of metabolites were determined using UV-HPLC and LC/MS/MS respectively. The maximum quantity of resistance genes was also examined at the beginning of AD tests and concentration was in the order of: tetM >tetO. The numbers of ARGs were always higher at high volatile solids (VS) content and high mixing rate. The results of the investigation revealed that relationship between mixing rate and VS content plays a crucial role for elimination of ARGs, OTC and metabolites. This can be attributed to high abundance of microorganisms due to high VS content and their increased contact with elevated mixing rate. An increased interaction between microorganisms triggers the promotion of ARGs.
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•Dominance of hydrogenotrophic methanogens over acetoclastic methanogens was observed.•Changes in microbial communities lead to changes in biodegradation capacity of OTC.•Numbers of ARGs were always higher at high VS content and high mixing rate.•Optimum conditions can cease the dissemination of ARGs and metabolites of OTC.