北京地区菜田土壤抗生素抗性基因的分布特征

为研究北京地区菜田土壤抗生素抗性基因(antibiotic resistance genes,ARGs)的污染状况和分布特征,采集了11个长期施用粪肥蔬菜基地的温室土壤和大田土壤,进行了抗生素以及ARGs种类和丰度的检测.结果表明,菜田土壤中四环素类抗生素残留量最高,其次为磺胺类抗生素,温室土壤抗生素残留普遍高于大田土壤.温室和大田土壤磺胺类抗性基因sul1、sul2和四环素类抗性基因tet L的检出率均为100%.温室土壤的Ⅰ类整合子(int I1)检出率比大田土壤高1.5倍.定量PCR的检测结果表明,菜田土壤中sul2和tet L的相对丰度介于10-4~10-2之间,温室土壤sul2和tet L的相对丰度普遍高于大田土壤.sul2的相对丰度与磺胺二甲嘧啶和强力霉素的含量显著正相关(P0.05),tet L相对丰度与抗生素含量无明显相关性(P0.05).本研究结果对于掌握北京地区农田土壤ARGs的污染现状,以及从ARGs角度评估农艺措施具有重要的指导意义.

Distribution Characteristics of Antibiotic Resistance Genes in Vegetable Soils in Beijing

In order to study the distribution characteristics and pollution status of antibiotic resistance genes (ARGs) in the vegetable soils, greenhouse and field soil samples in 11 organic vegetable bases with long-term manure amended in Beijing were collected. All samples were subjected to the determination of 13-type antibiotics and related ARGs. The experimental results showed that tetracycline residues were the highest among all antibiotics tested, followed by sulfanilamides. Antibiotic residues were higher in greenhouse soils than in field soils. For all soil samples, sulfanilamide resistance genes sul 1 and sul 2, as well as the tetracycline resistance gene tetL were observed with 100% detection frequencies. Detection frequency for class I integron (intI 1) in greenhouse soils was 1.5 times higher than that in field soils. The relative abundance for sul 2 and tetL in soil samples ranged 10^-4-10^-2 as found by quantitative PCR (qPCR) detection. The relative abundance of sul 2 was significantly positively correlated with the contents of sulfadimidine and doxycycline (P<0.05), and the relative abundance of tetL did not exhibit evident correlation with the contents of antibiotics tested. These results would contribute to understanding of the pollution status of ARGs in vegetable soils in Beijing, and to evaluation of currently agricultural practices based on ARGs.