摘要
      质粒结合在很大程度上促进了抗生素抗性基因（ARGs）在土壤中的传播。然而，对土壤动物肠道中ARGs传播潜力的研究仍然很少，宿主年龄对ARGs在土壤动物肠道微生物群中传播的影响也知之甚少。在此，以典型线虫秀丽隐杆线虫为模型土壤动物，旨在研究在不同温度梯度（15、20和25°C）下，利用qPCR结合平板筛选，在6天内从大肠杆菌MG1655向肠道微生物群转移广泛的宿主范围IncP-1。结果表明，秀丽隐杆线虫肠道中的结合率随着培养时间和温度的升高而增加，与大量的质粒结合相关基因如trbBp（交配对形成）和trfAp（质粒复制）具有相似的趋势。培养时间和温度显著影响了秀丽隐杆线虫的肠道微生物群落。秀丽隐杆线虫肠道中的核心微生物群，包括肠杆菌科、乳杆菌科和明串珠菌科，构成了质粒IncP-1的大部分跨共轭库。我们的研究结果强调了肠道微生物群在ARGs传播中的重要汇点，以及随着宿主年龄的增长，ARGs在肠道微生物群中的转移上调，这可能进一步刺激ARG在陆地环境中的进化。
Abstract
Plasmid conjugation contributes greatly to the spread of antibiotic resistance genes (ARGs) in soils. However, the spread potential in the gut of soil fauna remains poorly studied, and little was known about the impact of host age on ARGs dissemination in the gut microbiota of soil animals. Here, the typical nematode-Caenorhabditis elegans was employed as the model soil animal, aiming to investigate transfer of broad-host-range IncP-1ɛ from Escherichia coli MG1655 to gut microbiota within 6 days under varied temperature gradients (15, 20 and 25 °C) using qPCR combined with plate screening. Results showed that conjugation rates increased with incubation time and rising temperature in the gut of C. elegans, sharing a similar trend with abundances of plasmid conjugation relevant genes such as trbBp (mating pair formation) and trfAp (plasmid replication). Incubation time and temperature significantly shaped the gut microbial community of C. elegans. Core microbiota in the gut of C. elegans, including Enterobacteriaceae, Lactobacillaceae and Leuconostocaceae, constituted a large part of transconjugal pool for plasmid IncP-1ɛ. Our results highlight an important sink of gut microbiota for ARGs dissemination and upregulation of ARGs transfer in the gut microbiota with host age, further potentially stimulating evolution of ARGs in terrestrial environments.

https://www.sciencedirect.com/science/article/abs/pii/S0304389421024936