Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
Environ Int. 2013 Nov;61:1-7. doi: 10.1016/j.envint.2013.08.023. Epub 2013 Oct 2.
Increases of antibiotic resistance genes in the environment may pose a threat to public health. The purpose of this study was to investigate the abundance and diversity of tetracycline (tet) and sulfonamide (sul) resistance genes in eight livestock farms in Hangzhou, eastern China. Ten tet genes (tetA, tetB, tetC, tetG, tetL, tetM, tetO, tetQ, tetW, and tetX), two sul genes (sulI and sulII), and one genetic element associated with mobile antibiotic resistance genes [class 1 integron (intI1)] were quantified by real-time polymerase chain reaction. No significant difference was found in the abundance of the tet and sul genes in various scales of pig, chicken, and duck farms (P>0.05). The average abundance of ribosomal protection protein genes (tetQ, tetM, tetW, and tetO) in the manure and wastewater samples was higher than most of the efflux pump genes (tetA, tetB, tetC, and tetL) and enzymatic modification gene (tetX) (P<0.05), except for efflux pump gene tetG, which was abundant and showed no difference from tetM. Most ARGs had higher relative abundance in the wastewater lagoon than in manures even after treatment. Although the three ribosomal protection protein genes (tetQ, tetW, and tetO) had higher relative abundance, numbers were reduced during the complete wastewater treatment process in pig farms (P<0.05). The relative abundance of tetG, sulI, and sulII increased after the wastewater treatment and the removal of these three genes exhibited significant positive correlations with the intI1 gene (tetG: R(2)=0.60, P<0.05; sulI: R(2)=0.72, P<0.05; sulII: R(2)=0.62, P<0.05), suggesting that intI1 may be involved in their proliferation. As for tetM and sulII genes, a highly significant difference was found in manure samples between pig farms and duck farms (P<0.001). Phylogenetic analysis showed that tetM was more diverse in duck farms than in pig farms. Additionally, sulII sequence was conserved both in pig and duck farms. This is the first comprehensive study to detail the relative abundance of specific ARGs in animal manures and agricultural wastewater treatment systems, potentially providing knowledge for managing antibiotic resistance emanating from agricultural activities.
抗生素耐药基因在环境中的增加可能对公共健康构成威胁。本研究旨在调查中国东部杭州市 8 个养殖场中四环素（tet）和磺胺类（sul）耐药基因的丰度和多样性。通过实时聚合酶链反应定量检测了 10 个 tet 基因（tetA、tetB、tetC、tetG、tetL、tetM、tetO、tetQ、tetW 和 tetX）、2 个 sul 基因（sulI 和 sulII）和一个与移动抗生素耐药基因相关的遗传元件[1 类整合子（intI1）]。不同规模的猪、鸡和鸭养殖场的 tet 和 sul 基因丰度无显著差异（P＞0.05）。粪便和废水中核糖体保护蛋白基因（tetQ、tetM、tetW 和 tetO）的平均丰度高于大多数外排泵基因（tetA、tetB、tetC 和 tetL）和酶修饰基因（tetX）（P＜0.05），除了丰度较高且与 tetM 无差异的外排泵基因 tetG 外。即使经过处理，废水塘中的大多数 ARGs 相对丰度仍高于粪便。尽管 3 个核糖体保护蛋白基因（tetQ、tetW 和 tetO）的相对丰度较高，但在猪养殖场的整个废水处理过程中数量减少（P＜0.05）。废水处理后，tetG、sulI 和 sulII 的相对丰度增加，这三个基因的去除与 intI1 基因呈显著正相关（tetG：R²=0.60，P＜0.05；sulI：R²=0.72，P＜0.05；sulII：R²=0.62，P＜0.05），表明 intI1 可能参与了它们的增殖。对于 tetM 和 sulII 基因，猪养殖场和鸭养殖场的粪便样本中存在显著差异（P＜0.001）。系统发育分析表明，鸭养殖场的 tetM 比猪养殖场更为多样化。此外，猪和鸭养殖场的 sulII 序列都很保守。这是首次详细描述动物粪便和农业废水处理系统中特定 ARG 相对丰度的综合研究，可能为管理农业活动产生的抗生素耐药性提供知识。
