|关键词: 水环境 整合酶基因 耐药基因 高通量测序
|Distribution Characteristics of Integrase Genes in Typical Water Environment
LI Zi-han, ZHANG Xu-xiang, REN Hong-qiang
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China
|The abuse of antibiotics, along with the problem of antibiotic resistance of microorganisms caused by them, makes a serious threat on human health and is also a hotspot in environmental field at home and abroad. The health risks of antibiotics in the environment mainly come from antibiotic resistant bacteria and their antibiotic resistant genes (ARGs), and the horizontal transfer of ARGs is a key step to evaluate their health risks. Integron is an important genetic element which induce horizontal transfer of ARGs, as well as a key element that leads to multiple antibiotic resistance and the generation of superbacteria. Meanwhile, integrase gene (intI) can encode tyrosine recombinases to catalyzes recombination of captured gene cassettes (GCs) containing different antibiotic resistance genes (ARGs), resulting in the horizontal transfer of ARGs and the multi drug resistance of bacteria. A metagenomic analysis method based on DNA high throughput sequencing was used to compare the diversity and abundance difference of integrons, as well as their correlationship with ARGs in drinking water, domestic wastewater, aquacultural wastewater and medical wastewater. The results showed that five well classified integrase genes, intI1, intI2,intI3,intI6, and intI9, were found in four typical water environments by metagenomic analysis and comparison with INTEGRALL database. The total abundance ranked as follows: domestic wastewater>aquaculture wastewater>drinking water, and medical wastewater>drinking water. The diversity arranged a sequence of medictal wastewater>domestic wastewater>aquaculture wastewater>drinking water. The degree of uniformity sequenced in the order of medical wastewater>domestic wastewater>drinking water, and medical wastewater>aquaculture wastewater>drinking water. There is a similarity between domestic wastewater and aquaculture wastewater on the gene composition and abundance of intI, as well as that of drinking water, aquaculture wastewater, and medical wastewater. Among the five integrase genes, intI1 was widely distributed and had high abundance, and there was a strong correlation between intI1 and the abundance of five antibiotic resistance genes including sulfonamide, tetracycline, chloramphenicol, macrolide lincosamide streptogramin (MLS), and trimethoprim ARGs (r≥ 0.6, P<0.05).
|Key words: Water environment Integrase gene Antibiotic resistance genes High-throughput sequencing