Veterinary Antibiotic Effects on Atrazine Degradation and Soil Microorganisms

Abstract

Veterinary antibiotics (VAs) in manure applied to agricultural lands may change agrichemical degradation by altering soil microbial community structure or function. The objectives of this study were to investigate the influence of two VAs, sulfamethazine (SMZ) and oxytetracycline (OTC), on atrazine (ATZ) degradation, soil microbial enzymatic activity, and phospholipid fatty acid (PLFA) markers. Sandy loam soil with and without 5% swine manure (w/w) was amended with 0 or 500 μg kgC radiolabeled ATZ and with 0, 100, or 1000 μg kg SMZ or OTC and incubated at 25°C in the dark for 96 d. The half-life of ATZ was not significantly affected by VA treatment in the presence or absence of manure; however, the VAs significantly ( < 0.05) inhibited ATZ mineralization in soil without manure (25-50% reduction). Manure amendment decreased ATZ degradation by 22%, reduced ATZ mineralization by 50%, and increased the half-life of ATZ by >10 d. The VAs had limited adverse effects on the microbial enzymes β-glucosidase and dehydrogenase in soils with and without manure. In contrast, manure application stimulated dehydrogenase activity and altered chlorinated ATZ metabolite profiles. Concentrations of PLFA markers were reduced by additions of ATZ, manure, OTC, and SMZ; adverse additive effects of combined treatments were noted for arbuscular mycorrhizal fungi and actinobacteria. In this work, the VAs did not influence persistence of the ATZ parent compound or chlorinated ATZ metabolite formation and degradation. However, reduced CO evolved from VA-treated soil suggests an inhibition to the degradation of other ATZ metabolites due to an altered soil microbial community structure.

Effects of Tetracyclines on Enzymatic Activity and Soil Nutrient Availability

“…3 and Fig. 6, Nordenholt et al 2016). The reduction of GLU activity over time was less pronounced than that of the other enzymes studied.…”

“…After this period, there was a decrease in enzymatic activity as a function of the reduction of OM and available nutrients due to microbial consumption (Weintraub et al 2013). However, when SW is contaminated with tetracyclines, the reduction of enzyme activity may occur due to the antibiotics deleterious effects on the soil microbiota (Chen et al 2013;Fernández et al 2004;Gutiérrez et al 2010;Kotzerke et al 2008;Liu et al 2009;Nordenholt et al 2016;Qin et al 2019). For this study, the negative effects of tetracyclines on the enzymatic activities of DHA, GLU, ACP, and URE were observed during the course of two experiments.…”

Antibiotic resistance genes in different animal manures and their derived organic fertilizer

“…According to previous studies, the content of enro oxacin and cipro oxacin in chicken manure were 61 300 μg/kg and 18 800 μg/kg, respectively [6]. High levels of residual antibiotics in manure provided selective pressure to the native microbial communities after the application of manure in soil [7][8][9], and bacteria could acquire antibiotic resistance genes (ARGs) via horizontal gene transfer or spontaneous mutation, thereby causing the proliferation of resistant bacteria [10][11].…”

Effect of composting and soil type on dissipation of veterinary antibiotics in land-applied manures

“…A major concern is that antibiotics released into soils could exert a selective pressure on the native microbial community (Cleary et al, 2016;Nordenholt et al, 2016) and enrich antibiotic resistant bacteria and resistance genes (Jechalke et al, 2014).…”