医疗废物堆置场地土壤抗生素抗性基因组成特征——以华东丘陵地区某医废堆场为例

Characteristics of antibiotic resistance genes in the soil of a medical waste disposal site: A case study of a disposal site in the hilly area of eastern China

抗生素抗性基因(Antibiotic resistance genes,ARGs)目前已经被认为是一种重要的环境污染物;土壤中存在的微生物代表了ARGs的古老进化起源之一,并且已被认为是临床病原体获得ARGs的重要交换介质.为测试医疗废物堆置区域的ARGs丰度,在医废堆置区内外采集了共28个土壤样品.在提取样品中的微生物宏基因组之后,对所提取的DNA进行高通量测序.将所得序列与抗生素抗性基因数据库进行比对,并通过计算不同类型以及不同亚型的ARGs拷贝数/16S rRNA基因拷贝数评估ARGs的组成.结果显示,医废堆置区内样本所含的氨基糖苷类、氯霉素类、磺胺类、四环素类ARGs丰度显著高于堆置区外样本(分别达到了0.0134±0.0138、0.00615±0.00747、0.0188±0.0254以及0.00504±0.00292 ARGs拷贝数/16S rRNA基因拷贝数),特别是sul1(磺胺类)、flo R(氯霉素类)、cat B(氯霉素类)、aph(3’’)-I(氨基糖苷类)和tet G(四环素类)这5类ARGs亚型;同时,医废堆置区内样本有着更高的ARGs多样性(t-test,P <0.05).本研究表明医疗废物堆置会显著提高区域内土壤中ARGs的丰度以及多样性,从而增加潜在环境风险.

Antibiotic resistance genes(ARGs) are considered globally emergent pollutants in many environmental systems.Microorganisms in soil represent an evolutionary origin of ARGs and have been proposed as a reservoir for ARGs exchanging with clinical pathogens. To test the ARG profiles in the target medical waste dumping area, 28 different soil samples were taken from the area with medical waste and the nearby area. Metagenomes of the microorganisms from the soil sample were extracted for high-throughput sequencing. ARG abundances in these samples were then obtained by searching the metagenomic sequences against the antibiotic resistance genes database and by evaluating ARGs per copy of the 16 S rRNA gene at the type level and subtype level. Overall, compared to the nearby samples, the samples from the area with medical waste was significantly enriched with the ARGs encoding resistances to aminoglycoside, chloramphenicol, sulfonamide, and tetracycline(achieved 0.0134 ± 0.0138, 0.00615 ± 0.00747, 0.0188 ± 0.0254, and 0.00504 ± 0.00292 ARGs copy number/16 S rRNA gene copy number, respectively). This was especially true for the ARG subtypes of sul1(sulfonamide), flo R(chloramphenicol), cat B(chloramphenicol), aph(3'')-I(aminoglycoside), and tet G(tetracycline). Moreover, the diversity of ARGs in the samples from the polluted area was significantly higher than that of other samples(t-test, P <0.05). The comparatively high abundance and diversity of ARGs indicated the potential health risk of the medical wastes in the soil in the area.