摘要
      本研究调查了在锰矿恢复区（RA）和对照区（CA，远离RA）附近，抗生素抗性基因（ARGs）和病原体通过传播链（桑叶-蚕内脏-蚕粪便-土壤）的扩散和富集。ARGs的水平基因转移（HGT）通过携带ARGs（tetA）和偶联基因（例如，korB、trbA和trbB）作为指示剂的IncP a型宽宿主范围质粒RP4证实。与叶片相比，蚕食RA叶片后粪便中ARGs和病原体的丰度分别增加了10.8%和52.3%，而CA粪便中ARG和病原体的含量分别下降了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、肽和利福霉素的耐药性。其中，病原体携带的几种高风险ARG（如qnrB、oqxA和rpoB）在粪便中更富集。然而，由于质粒RP4宿主大肠杆菌在家蚕肠道的恶劣生存环境，在该传递链中由质粒RP4介导的HGT不是促进ARGs富集的主要因素。值得注意的是，粪便和肠道中的Zn、Mn和As促进了qnrB和oqxA的富集。令人担忧的是，无论粪便中是否含有大肠杆菌RP4，将RA粪便加入土壤30天后，土壤中qnrB和oqxA的丰度都增加了4倍以上。总的来说，ARGs和病原体可以通过RA形成的蚕业传播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，应更加重视消除这种高风险的ARG，以支持蚕业的良性发展，安全利用一些RA。
Abstract
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.

https://www.sciencedirect.com/science/article/abs/pii/S0013935123004085