School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, Shaanxi 710129, China; College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
Sci Total Environ. 2020 Nov 15;743:140759. doi: 10.1016/j.scitotenv.2020.140759. Epub 2020 Jul 6.
The abuse of heavy metals as feed additives in livestock is widespread and it might aggravate the spread of antibiotic resistance genes (ARGs) in the environment. However, the mechanisms that allow heavy metals to increase the transmission of ARGs in the environment remain unclear. Cu is the heavy metal present at the highest concentration in livestock manure, and thus Cu was selected to investigate the responses of ARGs to heavy metals. The effects of the microbial communities, mobile genetic elements (MGEs), and heavy metal resistance genes (HMRGs) on ARGs were determined in the presence of 75 and 227 mg L Cu in a swine manure anaerobic digestion (AD) system. In the AD products, the presence of residual Cu (75 and 227 mg L) increased the total ARGs, HMRGs, and some MGEs, and the higher Cu selected more ARGs than the lower Cu treatment. The results demonstrated that Cu could promote the co-selection of HMRGs, ARGs, and MGEs. The different levels of Cu did not change the bacterial community composition, but they influenced the abundances of bacteria during AD. Network analysis showed that the presence of Cu increased the co-occurrence of specific bacteria containing ARGs, HMRGs, and MGEs. Furthermore, the co-occurrence of MGEs and ARGs increased greatly compared with that of HMRGs and ARGs. Therefore, compared HMRGs, the increased MGEs had the main effect on increasing of ARGs.
重金属作为饲料添加剂在畜牧业中的滥用现象普遍存在，这可能会加剧环境中抗生素耐药基因（ARGs）的传播。然而，重金属允许 ARGs 在环境中传播的机制仍不清楚。Cu 是畜禽粪便中含量最高的重金属，因此选择 Cu 来研究重金属对 ARGs 的响应。在猪粪厌氧消化（AD）系统中，分别添加 75 和 227mg/L 的 Cu，研究了微生物群落、可移动遗传元件（MGEs）和重金属抗性基因（HMRGs）对 ARGs 的影响。在 AD 产物中，残留 Cu（75 和 227mg/L）的存在增加了总 ARGs、HMRGs 和一些 MGEs，并且较高的 Cu 选择了比低 Cu 处理更多的 ARGs。结果表明，Cu 可以促进 HMRGs、ARGs 和 MGEs 的共同选择。不同水平的 Cu 不会改变细菌群落组成，但会影响 AD 过程中细菌的丰度。网络分析表明，Cu 的存在增加了含有 ARGs、HMRGs 和 MGEs 的特定细菌的共现。此外，与 HMRGs 和 ARGs 的共现相比，MGEs 和 ARGs 的共现大大增加。因此，与 HMRGs 相比，增加的 MGEs 对 ARGs 的增加有主要影响。
