Yan Kanxuan, Wei Ming, Li Feng, Wu Chen, Yi Shengwei, Tian Jiang, Liu Yun, Lu Hainan
College of Environment Science and Resources, Xiangtan University, Xiangtan, 411105, China; Hunan Engineering Laboratory for High-efficiency Purification Technology and Its Application in Complex Heavy Metal Wastewater Treatment, Xiangtan, 411105, China; Scientific Research Innovation Platform of Environmental Behavior and Control Principle About Novel Pollutants in Hunan Provincial Universities, Xiangtan, 411105, China.
College of Environment Science and Resources, Xiangtan University, Xiangtan, 411105, China; Hunan Engineering Laboratory for High-efficiency Purification Technology and Its Application in Complex Heavy Metal Wastewater Treatment, Xiangtan, 411105, China; Scientific Research Innovation Platform of Environmental Behavior and Control Principle About Novel Pollutants in Hunan Provincial Universities, Xiangtan, 411105, China.
Environ Res. 2023 May 15;225:115616. doi: 10.1016/j.envres.2023.115616. Epub 2023 Mar 5.
This study investigated the diffusion and enrichment of antibiotic resistance genes (ARGs) and pathogens via the transmission chain (mulberry leaves - silkworm guts - silkworm feces - soil) near a manganese mine restoration area (RA) and control area (CA, away from RA). Horizontal gene transfer (HGT) of ARGs was testified by an IncP a-type broad host range plasmid RP4 harboring ARGs (tetA) and conjugative genes (e.g., korB, trbA, and trbB) as an indicator. Compared to leaves, the abundances of ARGs and pathogens in feces after silkworms ingested leaves from RA increased by 10.8% and 52.3%, respectively, whereas their abundance in feces from CA dropped by 17.1% and 97.7%, respectively. The predominant ARG types in feces involved the resistances to β-lactam, quinolone, multidrug, peptide, and rifamycin. Therein, several high-risk ARGs (e.g., qnrB, oqxA, and rpoB) carried by pathogens were more enriched in feces. However, HGT mediated by plasmid RP4 in this transmission chain was not a main factor to promote the enrichment of ARGs due to the harsh survival environment of silkworm guts for the plasmid RP4 host E. coli. Notably, Zn, Mn, and As in feces and guts promoted the enrichment of qnrB and oqxA. Worriedly, the abundance of qnrB and oqxA in soil increased by over 4-fold after feces from RA were added into soil for 30 days regardless of feces with or without E. coli RP4. Overall, ARGs and pathogens could diffuse and enrich in environment via the sericulture transmission chain developed at RA, especially some high-risk ARGs carried by pathogens. Thus, greater attentions should be paid to dispel such high-risk ARGs to support benign development of sericulture industry in the safe utilization of some RAs.
本研究调查了锰矿修复区（RA）及对照区（CA，远离RA）附近通过传输链（桑叶-蚕肠道-蚕粪便-土壤）的抗生素抗性基因（ARGs）和病原体的扩散与富集情况。以携带ARGs（tetA）和接合基因（如korB、trbA和trbB）的IncP a型广宿主范围质粒RP4作为指标来证实ARGs的水平基因转移（HGT）。与桑叶相比，蚕摄食RA的桑叶后粪便中ARGs和病原体的丰度分别增加了10.8%和52.3%，而CA粪便中它们的丰度分别下降了17.1%和97.7%。粪便中主要的ARG类型涉及对β-内酰胺、喹诺酮、多药、肽和利福霉素的抗性。其中，病原体携带的几种高风险ARGs（如qnrB、oqxA和rpoB）在粪便中富集程度更高。然而，由于质粒RP4宿主大肠杆菌在蚕肠道中的生存环境恶劣，该传输链中由质粒RP4介导的HGT并非促进ARGs富集的主要因素。值得注意的是，粪便和肠道中的锌、锰和砷促进了qnrB和oqxA的富集。令人担忧的是，将RA的粪便添加到土壤中30天后，无论粪便中有无大肠杆菌RP4，土壤中qnrB和oqxA的丰度均增加了4倍以上。总体而言，ARGs和病原体可通过RA形成的养蚕传输链在环境中扩散和富集，尤其是病原体携带的一些高风险ARGs。因此，在一些修复区的安全利用中，应更加重视消除此类高风险ARGs，以支持养蚕业的良性发展。
