Abstract. The widespread use of both heavy metals and antibiotics in livestock farming and their subsequent arrival on agricultural soils through manure/slurry spreading has become a problem of vital importance for human health and the environment. In the current research, a laboratory experiment was carried out for 42 days to study co-selection for tolerance of three tetracycline antibiotics (tetracycline, TC; oxytetracycline, OTC; chlortetracycline, CTC) in soils polluted with heavy metals (As, Cd, Zn, Cu, Ni, Cr and Pb) at high concentration levels (1000 mg kg⁻¹ of each one, separately). Pollution Induced Community Tolerance (PICT) of the bacterial community was estimated using the leucine incorporation technique. The Log IC₅₀ (logarithm of the concentration causing 50 % inhibition in bacterial community growth) values obtained in uncontaminated soil samples for all the heavy metals tested showed the following toxicity sequence: Cu > As > Cr ≥ Pb ≥ Cd > Zn > Ni. However, in polluted soil samples the toxicity sequence was: Cu > Pb ≥ As ≥ Cd ≥ Cr ≥ Ni ≥ Zn. Moreover, at high metal concentrations the bacterial communities show tolerance to the metal itself, this taking place for all the metals tested in the long term. The bacterial communities of the soil polluted with heavy metals showed also long-term co-tolerance to TC, OTC, and CTC. This kind of studies, focusing on the eventual increases of tolerance and co-tolerance of bacterial communities in agricultural soil, favored by the presence of other pollutants, is of crucial importance, mostly bearing in mind that the appearance of antibiotic resistance genes in soil bacteria could be transmitted to human pathogens.

中文翻译：

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土壤细菌群落对 As、Cd、Zn、Cu、Ni、Cr 和 Pb 污染诱导的四环素类抗生素的耐受性

摘要。重金属和抗生素在畜牧业中的广泛使用以及它们随后通过粪便/泥浆扩散进入农业土壤已成为对人类健康和环境至关重要的问题。在目前的研究中，进行了为期 42 天的室内试验，研究了在重金属（As、Cd、Zn 、Cu、Ni、Cr 和 Pb）在高浓度水平（分别为 1000 mg kg ^-1）。使用亮氨酸掺入技术估计细菌群落的污染诱导群落耐受性（PICT）。日志 IC ₅₀（导致细菌群落生长抑制 50% 的浓度的对数）在未受污染的土壤样品中获得的所有重金属测试值显示以下毒性序列：Cu > As > Cr ≥ Pb ≥ Cd > Zn > Ni。然而，在污染土壤样品中，毒性顺序为：Cu > Pb ≥ As ≥ Cd ≥ Cr ≥ Ni ≥ Zn。此外，在高金属浓度下，细菌群落对金属本身表现出耐受性，这发生在长期测试的所有金属中。被重金属污染的土壤的细菌群落也表现出对 TC、OTC 和 CTC 的长期共耐受性。这类研究侧重于农业土壤中细菌群落的耐受性和共耐受性的最终增加，受其他污染物的存在的青睐，具有至关重要的意义，