Pollution-Induced Tolerance of Soil Bacterial Communities to Oxytetracycline-Spiked Manure

Abstract

The use of manure as a fertilizer is a common agricultural practice that can improve soil physicochemical and biological properties. However, antibiotics and their metabolites are often present, leading to the adaptation of soil bacterial communities to their presence. The aim of this study was to assess the effects of the extensively used, broad-spectrum antibiotic oxytetracycline on soil microbial community adaptation using a pollution-induced community tolerance assay. Manure-amended soil was spiked with oxytetracycline (0, 2, 20, 60, 150, and 500 mg kg−1) three times every ten days in the selection phase. The detection phase was conducted in Biolog EcoPlates with a second oxytetracycline exposure (0, 5, 20, 40, 60, and 100 mg L−1). All treatments demonstrated decreased metabolic activity after exposure to ≥ 5 mg L−1 oxytetracycline during the detection phase. Meanwhile, a significant increase in tolerance was observed following exposure to ≥ 20 mg oxytetracycline per kg soil during the selection phase. Therefore, the pollution-induced community tolerance approach with Biolog EcoPlates was a useful system for the detection of antibiotic selection pressures on soil bacterial communities. It is important to properly manage animal waste before their application to the soil to reduce the occurrence of antibiotic-resistance in the environment.

Appraisal of biological remediation options for the recovery of a mixed contaminated soil from a gravel pit

“…When double interactions between factors were signi cant (p < 0.05), differences were tested using Duncan's post-hoc test with agricolae package (Jauregi et al 2021). Redundancy analyses (RDA) were used to explore the effect of treatments on soil parameters using CANOCO 5.0 (ter Braak and Šmilauer 2012).…”

“…Colour development was read at 595 nm using a micro plate reader (Anthos Zenyth 3100). species abundance(Jauregi et al 2021). Kinetic parameters were estimated by adjusting nonlinear curves to the Gompertz function (Lindstrom et al 1998), according to the following equation:…”

“…Average well colour development (AWCD) was determined by calculating the mean of every well's absorbance value at each reading time. The incubation time corresponding to the midpoint of the exponential growth phase was chosen for further calculations(Jauregi et al 2021). The number of utilized substrates (NUS), equivalent to species richness (S), was calculated at the beginning of the exponential phase(Epelde et al 2008).…”