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- Title
Toxicity of the Colistin Sulfate Antibiotic Used in Animal Farming to Mixed Cultures of Nitrifying Organisms.
- Authors
Bressan, C.; Kunz, A.; Schmidell, W.; Soares, H.
- Abstract
Colistin is a peptide antibiotic widely used as a food additive in animal farming, specially swine and poultry, and also has recently been applied in human medicine to treat infections caused by multiresistant gram-negative bacteria strains. When orally administered, colistin is eliminated in feces virtually unaltered; thus, it may reach water bodies and wastewater treatment facilities in its active form. Apart from the risks associated with development of antimicrobial resistance and environmental toxicity issues, the presence of antimicrobials in wastewater can, additionally, interfere in biological processes commonly used to treat them. Nitrifying bacteria are among the most sensitive microorganisms to inhibitory compounds, including pharmaceuticals, and are useful as biosensors to access contaminant toxicity information in wastewater treatment plants. Therefore, in order to assess the colistin acute toxicity to the microorganisms involved in the nitrification processes, the nitritation and nitratation kinetics were monitored under different colistin concentrations. The results showed that only ammonia-oxidizing bacteria are sensitive to the antibiotic, presenting an IC50 of 10.8 mg L of colistin when used as a commercial formulation and 67.0 mg L when used as raw colistin sulfate. For nitrite-oxidizing bacteria, even the highest colistin concentration used in the assays (316 mg L) was not sufficient to inhibit the process. According to these results, the colistin concentrations expected in animal farming wastewater, when its dosage is used as a growth promoter, would not be enough to keep nitrification from taking place. Nevertheless, when used in higher concentrations, such as for therapeutic purposes, it could endanger the maintenance of the process.
- Subjects
COLISTIN; MIXED culture (Microbiology); NITRIFYING bacteria; SWINE farms; POULTRY farms
- Publication
Water, Air & Soil Pollution, 2013, Vol 224, Issue 3, p1
- ISSN
0049-6979
- Publication type
Article
- DOI
10.1007/s11270-013-1441-4