College of Animal Science, National Engineering Research Center for Breeding Swine Industry, South China Agricultural University, Guangzhou 510642, China.
College of Animal Science, National Engineering Research Center for Breeding Swine Industry, South China Agricultural University, Guangzhou 510642, China; Ministry of Agriculture Key Laboratory of Tropical Agricultural Environment, South China Agricultural University, Guangzhou 510642, China; Guangdong Enterprise Lab of Healthy Animal Husbandry and Environment Control, Yunfu, Xinxing 527400, China.
Ecotoxicol Environ Saf. 2018 Jan;147:759-766. doi: 10.1016/j.ecoenv.2017.09.025. Epub 2017 Oct 10.
Biodegradation of antibiotic residues in the environment by microorganisms may lead to the generation of antibiotic resistance genes (ARGs), which are of great concern to human health. The aim of this study was to determine whether there is a relationship between the ability to degrade antibiotic doxycycline (DOX) and the development of resistance genes in microorganisms. We isolated and identified ten bacterial strains from a vegetable field that had received long-term manure application as fertilizer and were capable of surviving in a series of DOX concentrations (25, 50, 80, and 100mg/L). Our results showed no evidential correlation between DOX degradation ability and the development of resistance genes among the isolated microorganisms that had high DOX degradation capability (P > 0.05). This was based on the fact that Escherichia sp. and Candida sp. were the most efficient bacterial strains to degrade DOX (92.52% and 91.63%, respectively), but their tetracycline resistance genes showed a relatively low risk of antibiotic resistance in a 7-day experiment. Moreover, the tetM of the ribosomal protection protein genes carried by these two preponderant bacteria was five-fold higher than that carried by other isolates (P < 0.05). Pearson correlations between the C/C of DOX and tet resistance genes of three isolates, except for Escherichia sp. and Candida sp., showed remarkable negative correlations (P < 0.05), mainly because tetG markedly increased during the DOX degradation process. Our results concluded that the biodegradation of antibiotic residues may not necessarily lead to the development of ARGs in the environment. In addition, the two bacteria that we isolated, namely, Escherichia sp. and Candida sp., are potential candidates for the engineering of environmentally friendly bacteria.
环境中微生物对抗生素残留的生物降解可能导致抗生素耐药基因（ARGs）的产生，这对人类健康有很大的影响。本研究旨在确定抗生素土霉素（DOX）降解能力与微生物耐药基因发展之间是否存在关系。我们从长期施用粪肥作为肥料的蔬菜田中分离并鉴定了十株能够在一系列 DOX 浓度（25、50、80 和 100mg/L）下存活的细菌。我们的结果表明，在具有高 DOX 降解能力的分离微生物中，DOX 降解能力与耐药基因的发展之间没有明显的相关性（P > 0.05）。这是基于以下事实：大肠杆菌和假丝酵母是降解 DOX 最有效的细菌菌株（分别为 92.52%和 91.63%），但它们的四环素耐药基因在 7 天的实验中显示出相对较低的抗生素耐药风险。此外，这两种优势菌携带的核糖体保护蛋白基因的 tetM 比其他分离株高五倍（P < 0.05）。除大肠杆菌和假丝酵母外，三种分离株中 DOX 的 C/C 与 tet 耐药基因之间的 Pearson 相关性呈显著负相关（P < 0.05），主要是因为在 DOX 降解过程中 tetG 明显增加。我们的研究结果表明，抗生素残留的生物降解不一定会导致环境中 ARGs 的发展。此外，我们分离的两种细菌，即大肠杆菌和假丝酵母，可能是工程菌的潜在候选菌。
