摘要

   牲畜中滥用重金属作为饲料添加剂的现象很普遍，这可能会加剧抗生素抗性基因（ARG）在环境中的传播。但是，尚不清楚允许重金属增加ARG在环境中的传播的机制。 Cu是家畜粪便中浓度最高的重金属，因此选择Cu来研究ARG对重金属的响应。在猪粪厌氧消化（AD）系统中，在存在75和227 mg L-1 Cu的条件下，确定了微生物群落，移动遗传元件（MGE）和重金属抗性基因（HMRG）对ARG的影响。在AD产品中，残留铜（75和227 mg L-1）的存在增加了总ARG，HMRG和某些MGE，并且较高的Cu比较低的Cu处理选择了更多的ARG。结果表明，Cu可以促进HMRG，ARG和MGE的共选。铜的不同含量不会改变细菌群落组成，但会影响AD期间细菌的丰度。网络分析表明，铜的存在增加了含有ARG，HMRG和MGE的特定细菌的共存。此外，与HMRG和ARGs相比，MGEs和ARGs的同时出现大大增加。因此，与HMRGs相比，增加的MGEs对ARGs的增加具有主要作用。

    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−1 Cu in a swine manure anaerobic digestion (AD) system. In the AD products, the presence of residual Cu (75 and 227 mg L−1) 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.

    https://www.sciencedirect.com/science/article/abs/pii/S0048969720342832