摘要

       随着饲料添加剂在畜牧业中的广泛应用，畜禽粪便已成为抗生素、重金属和抗生素耐药基因（ARGs）研究的热点。与抗生素不同的是，重金属在堆肥过程中不能降解，因此在抗生素耐药性的扩散过程中可能造成持续的共选择压力。钝化剂通常用于固定金属和提高堆肥的安全性。然而，人们对堆肥过程中各种钝化剂对ARGs和移动遗传元素（MGE）的影响及其相关机制知之甚少。因此，在富铜猪粪堆肥过程中，应用了三种典型的钝化剂（生物炭、粉煤灰和沸石），研究了它们对ARGs、铜抗性基因、MGE和细菌群落的影响。与对照相比，所有钝化剂处理使堆肥后至少6种ARGs（tetC、tetG、tetQ、tetX、sul1和ermB）的丰度降低了0.23-1.09原木，两种mge（intI1和ISCR1）的丰度降低了26-85%。生物炭和粉煤灰也显著降低了intI2和Tn914/1545的丰度。相反，铜抗性基因的丰度并没有被钝化剂降低，这意味着在本研究中降低的共选择压力可能不是导致ARGs降低的主要原因。Procrustes分析和冗余分析表明，细菌群落的变化决定了ARGs丰度的变化，MGEs和DTPA-Cu的变化也可以部分解释ARG的变化。总的来说，三种钝化剂都可以用来降低与畜禽粪便中ARGs相关的健康风险，而生物炭在降低ARGs和MGE方面表现最好。

       Due to the intensive use of feed additives in livestock farming, animal manure has become a hotspot for antibiotics, heavy metals, and antibiotic resistance genes (ARGs). Unlike antibiotics, heavy metals cannot be degraded during composting and thus could pose a persistent co-selective pressure in the proliferation of antibiotic resistance. Passivators are commonly applied to immobilize metals and improve the safety of compost. However, little is known about the effects of various passivators on ARGs and mobile genetic elements (MGEs) during composting and the underlying mechanisms involved. Thus, three typical passivators (biochar, fly ash, and zeolite) were applied during the composting of copper-enriched pig manure, and their effects on ARGs, copper resistance genes, MGEs, and the bacterial communities were examined. Compared to the control, all passivator treatments reduced the abundances of at least six ARGs (tetC, tetG, tetQ, tetX, sul1, and ermB) by 0.23-1.09 logs and of two MGEs (intI1 and ISCR1) by 26-85% after composting. Biochar and fly ash also significantly reduced the abundances of intI2 and Tn914/1545. In contrast, abundances of copper resistance genes were not reduced by passivators, implying that the decreased co-selective pressure may not be a major contributor to ARG reductions in this study. Procrustes analysis and redundancy analysis demonstrated that shifts in the bacterial community determined the changes in the abundances of ARGs, and the variation in MGEs and DTPA-Cu can also partially explain the ARG variance. Overall, all of three passivators can be used to reduce the health risks associated with ARGs in livestock manure, and biochar performed the best at reducing ARGs and MGEs.

        https://www.sciencedirect.com/science/article/pii/S0048969719317267?via%3Dihub