摘要
      硅藻土（DE）已被用于粪便堆肥过程中的氮保护，但其对抗生素抗性基因（ARGs）的影响及其相关机制尚不清楚。在本研究中，在堆肥过程中，将DE以三种不同的比例（0%、4%和8%）添加到猪粪中。结果表明，添加DE有助于降低ARGs的丰度，最高剂量时ARGs含量下降幅度最大（88.99%）。DE修正促进了可还原铜转化为更稳定的形式，即残余部分，这降低了铜施加的选择压力，并进一步降低了ARGs的丰度。Tn916/1545和intI1是与ARGs相关的关键遗传成分，因此ARGs丰度的降低可能归因于由于移动遗传元件（MGE）丰度的降低而抑制了水平转移。微生物群落结构（细菌丰度和多样性）在ARGs的进化中起着关键作用。DE可以通过增加细菌群落多样性来增强ARGs宿主和非宿主之间的竞争。与CK相比，DE改良剂通过降低ARGs和棒状杆菌等病原体的潜在宿主的丰度来优化细菌群落，从而提高堆肥产品的安全性。此外，KEGG功能预测显示，添加DE会抑制代谢途径和与ARGs相关的基因。因此，8%DE的堆肥可以降低ARG传播的风险，并提高农业应用的实用价值。
Abstract
Diatomite (DE) has been used for nitrogen conservation during the composting of feces but its effects on antibiotic resistance genes (ARGs) and the associated mechanisms are still unclear. In this study, DE was added at three different proportions (0%, 4%, and 8%) to swine manure during composting. The results showed that adding DE helped to reduce the abundances of ARGs and the maximum decrease (88.99%) occurred with the highest dose. DE amendment promoted the transformation of reducible copper into a more stable form, i.e., the residual fraction, which reduced the selective pressure imposed by copper and further decreased the abundances of ARGs. Tn916/1545 and intI1 were critical genetic components related to ARGs, and thus the reductions in the abundances of ARGs may be attributed to the suppression of horizontal transfer due to the decreased abundances of mobile genetic elements (MGEs). The microbial community structure (bacterial abundance and diversity) played key role in the evolution of ARGs. DE could enhance the competition between hosts and non-hosts of ARGs by increasing the bacterial community diversity. Compared with CK, DE amendment optimized the bacterial community by reducing the abundances of the potential hosts of ARGs and pathogens such as Corynebacterium, thereby improving the safety of the compost product. In addition, KEGG function predictions revealed that adding DE inhibited the metabolic pathway and genes related to ARGs. Thus, composting with 8% DE can reduce the risk of ARG transmission and improve the practical value for agronomic applications.

https://www.sciencedirect.com/science/article/abs/pii/S0048969722002893