College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China; School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, Guangdong, 510000, China.
College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, China.
J Environ Manage. 2023 Sep 1;341:118071. doi: 10.1016/j.jenvman.2023.118071. Epub 2023 May 4.
Applying exogenous additives during the aerobic composting of livestock manure is effective for slowing down the spread of antibiotic resistance genes (ARGs) in the environment. Nanomaterials have received much attention because only low amounts need to be added and they have a high capacity for adsorbing pollutants. Intracellular ARGs (i-ARGs) and extracellular ARGs (e-ARGs) comprise the resistome in livestock manure but the effects of nanomaterials on the fates of these different fractions during composting are still unclear. Thus, we investigated the effects of adding SiO nanoparticles (SiONPs) at four levels (0 (CK), 0.5 (L), 1 (M), and 2 g/kg (H)) on i-ARGs, e-ARGs, and the bacterial community during composting. The results showed that i-ARGs represented the main fraction of ARGs during aerobic composting of swine manure, and their abundance was lowest under M. Compared with CK, M increased the removal rates of i-ARGs and e-ARGs by 17.9% and 100%, respectively. SiONPs enhanced the competition between ARGs hosts and non-hosts. M optimized the bacterial community by reducing the abundances of co-hosts (Clostridium_sensu_stricto_1, Terrisporobacter, and Turicibacter) of i-ARGs and e-ARGs (by 96.0% and 99.3%, respectively) and killing 49.9% of antibiotic-resistant bacteria. Horizontal gene transfer dominated by mobile genetic elements (MGEs) played a key role in the changes in the abundances of ARGs. i-intI1 and e-Tn916/1545 were key MGEs related closely to ARGs, and the maximum decreases of 52.8% and 100%, respectively, occurred under M, which mainly explained the decreased abundances of i-ARGs and e-ARGs. Our findings provide new insights into the distribution and main drivers of i-ARGs and e-ARGs, as well as demonstrating the possibility of adding 1 g/kg SiONPs to reduce the propagation of ARGs.
在好氧堆肥过程中添加外源添加剂可以有效减缓抗生素抗性基因（ARGs）在环境中的传播。纳米材料受到了广泛关注，因为只需添加少量的纳米材料就可以达到很高的污染物吸附能力。细胞内抗生素抗性基因（i-ARGs）和细胞外抗生素抗性基因（e-ARGs）构成了粪便中的抗药性组，但纳米材料对堆肥过程中这些不同部分命运的影响仍不清楚。因此，我们研究了在堆肥过程中添加四个不同水平（0（CK）、0.5（L）、1（M）和 2 g/kg（H））的 SiO 纳米粒子（SiONPs）对 i-ARGs、e-ARGs 和细菌群落的影响。结果表明，在猪粪好氧堆肥过程中，i-ARGs 是 ARGs 的主要组成部分，在 M 条件下其丰度最低。与 CK 相比，M 分别提高了 i-ARGs 和 e-ARGs 的去除率 17.9%和 100%。SiONPs 增强了 ARGs 宿主和非宿主之间的竞争。M 通过减少 i-ARGs 和 e-ARGs 的共宿主（Clostridium_sensu_stricto_1、Terrisporobacter 和 Turicibacter）的丰度（分别减少 96.0%和 99.3%）和杀死 49.9%的抗生素抗性细菌来优化细菌群落。以移动遗传元件（MGEs）为主导的水平基因转移在 ARGs 丰度变化中起着关键作用。i-intI1 和 e-Tn916/1545 是与 ARGs 密切相关的关键 MGEs，在 M 条件下，它们的丰度分别最大减少了 52.8%和 100%，这主要解释了 i-ARGs 和 e-ARGs 丰度的降低。我们的研究结果提供了有关 i-ARGs 和 e-ARGs 的分布和主要驱动因素的新见解，并证明了添加 1 g/kg SiONPs 以减少 ARGs 传播的可能性。
