摘要

       畜牧业过度使用重金属和抗生素导致重金属抗性基因（HMRGs）和抗生素抗性基因（ARGs）在环境中积累。本研究旨在揭示不同初始金霉素 (CTC) 浓度下粪便堆肥中 HMRGs 和 ARGs 的重金属形态和潜在水平基因转移 (HGT) 的变化。操作添加 20 mg/kg CTC（治疗 P1）、100 mg/kg CTC（治疗 P2）和对照（治疗 CK）的治疗。结果表明，无论初始浓度如何，CTC 都可以在所有处理的嗜热阶段完全去除。堆肥处理后，CK、P1 和 P2 处理中的生物可利用 Cu 分别下降 14.5%、27.1% 和 26.7%，生物可利用 Zn 分别下降 15.3%、29.5% 和 12.1%。在 CK、P1 和 P2 处理中，HMRGs 的相对丰度分别降低了 6.49 log、8.88 log 和 5.77 log。在 CK、P1 和 P2 处理中，ARG 的相对丰度分别降低了 3.37 log、4.86 log 和 3.32 log。堆肥可有效减少基因 pcoD、pcoA、zntA、tetQ 和 tetA，这些基因可能位于同一质粒上。 100 mg/kg 的 CTC 促进了 ARGs 和 HMRGs 的共同选择，并增加了基因 cusA 的潜在 HGT。

       Overuse of heavy metal and antibiotics in livestock husbandry has led to the accumulation of heavy metal resistance genes (HMRGs) and antibiotic resistance genes (ARGs) in environment. This research aims to reveal the variation of heavy metal speciation and potential horizontal gene transfer (HGT) of HMRGs and ARGs in manure composting under different initial chlortetracycline (CTC) concentrations. Treatments spiked with 20 mg/kg CTC (treatment P1), 100 mg/kg CTC (treatment P2), and the control (treatment CK) were operated. Results showed that CTC could be completely removed in the thermophilic phase of all the treatments despite of the initial concentrations. Bioavailable Cu in treatments CK, P1, and P2 declined by 14.5%, 27.1%, and 26.7% and bioavailable Zn declined by 15.3%, 29.5%, and 12.1%, respectively, after the composting, respectively. Relative abundance of HMRGs decreased by 6.49 log, 8.88 log, and 5.77 log, respectively, in treatments CK, P1, and P2. Relative abundance of ARGs decreased by 3.37 log, 4.86 log, and 3.32 log, respectively, in treatments CK, P1, and P2. Composting could effectively reduce genes pcoD, pcoA, zntA, tetQ, and tetA, which might locate on the same plasmid. CTC of 100 mg/kg promoted the co-selection of ARGs and HMRGs and increased the potential HGT of gene cusA.

https://link.springer.com/article/10.1007/s11356-020-10557-x