摘要

       中国畜牧业中抗生素的过度使用以及随之而来的动物粪便中抗生素抗性基因（ARGs）的选择增加令人严重关切。高温堆肥是减少有机废物危害的有效方法。然而，其在商业运营中抗生素降解和 ARG 减少的有效性仍不清楚。在本研究中，我们确定了中国东部由牛、家禽和猪粪制成的商业堆肥中 15 种常见兽用抗生素的浓度以及 213 个 ARG 和 10 个移动遗传元件 (MGE) 标记基因的丰度。在家禽和猪的堆肥中发现了高浓度的氟喹诺酮类药物，表明商业嗜热堆肥对这些抗生素的去除不足。牛和家禽粪便中的总 ARG 分别高达每个细菌细胞 1.9 和 5.5 个拷贝。高温堆肥后，成熟堆肥中ARG丰度分别下降到牛粪和家禽粪肥的9.6%和31.7%。然而，一些 ARG（例如 aadA、aadA2、qacEΔ1、tetL）和 MGE 标记基因（例如 cintI-1、intI-1 和 tnpA-04）在堆肥中以高丰度持续存在。在堆肥中检测到的高水平抗生素（例如诺氟沙星和氧氟沙星）可能对 ARG 构成了选择压力。发现 MGE 标记基因在单个基因、抗性类别和总丰度水平上与 ARG 密切相关，表明 MGE 和 ARG 在抗生素选择下它们在堆肥中的持久性密切相关。我们的研究表明，通过堆肥利用可能会传播抗生素和 ARG。

The over-use of antibiotics in animal husbandry in China and the concomitant enhanced selection of antibiotic resistance genes (ARGs) in animal manures are of serious concern. Thermophilic composting is an effective way of reducing hazards in organic wastes. However, its effectiveness in antibiotic degradation and ARG reduction in commercial operations remains unclear. In the present study, we determined the concentrations of 15 common veterinary antibiotics and the abundances of 213 ARGs and 10 marker genes for mobile genetic elements (MGEs) in commercial composts made from cattle, poultry and swine manures in Eastern China. High concentrations of fluoroquinolones were found in the poultry and swine composts, suggesting insufficient removal of these antibiotics by commercial thermophilic composting. Total ARGs in the cattle and poultry manures were as high as 1.9 and 5.5 copies per bacterial cell, respectively. After thermophilic composting, the ARG abundance in the mature compost decreased to 9.6% and 31.7% of that in the cattle and poultry manure, respectively. However, some ARGs (e.g. aadA, aadA2, qacEΔ1, tetL) and MGE marker genes (e.g. cintI-1, intI-1 and tnpA-04) were persistent with high abundance in the composts. The antibiotics that were detected at high levels in the composts (e.g. norfloxacin and ofloxacin) might have posed a selection pressure on ARGs. MGE marker genes were found to correlate closely with ARGs at the levels of individual gene, resistance class and total abundance, suggesting that MGEs and ARGs are closely associated in their persistence in the composts under antibiotic selection. Our research shows potential disseminations of antibiotics and ARGs via compost utilization.

https://www.sciencedirect.com/science/article/abs/pii/S0269749116308181