摘要

我们评估了土霉素（OTC）对包含抗生素的生物质在嗜温厌氧消化（AD）过程中的性能和抗生素耐药性发展的慢性影响。在完全搅拌的罐式反应器中进行中温AD，在20天内持续加入添加有浓度递增的OTC（0-1000mgL-1）的市政剩余污泥并固相保留265天。结果表明，由于发酵和产酸细菌的抑制，当消化污泥的OTC浓度增加到约18,000mgkg-1（OTC剂量，1000mgL-1）时，中温AD的甲烷产生被抑制。宏基因组测序和高通量定量PCR分析表明，四环素抗性基因在整个试验期内是最主要的抗性类型（38.47-43.76％），tetG，tetX，tetM，tetR，tetQ，tetO和tetL是主要的抗性亚型。这些tet基因的相对丰度从2.10×10-1增加到2.83×10-1（p <0.05），OTC剂量为40 mg·L - 1 (消化污泥中的OTC浓度，528.52 mg·kg - 1 )。此外，随着OTC剂量的增加，整合子、转座子和质粒等可移动遗传元件也不断丰富。基于部分典范对应分析，水平（移动元素改变）和垂直（细菌群落移位）基因转移对抗生素抗性组变异的贡献分别为29.35％和21.51％。因此，考虑到水解酸化抑制和抗生素耐药性富集，不建议中温AD直接处理含OTC浓度高于200mgL-1的生物量。

We evaluated the chronic impact of oxytetracycline (OTC) on performance and antibiotic resistance development during the mesophilic anaerobic digestion (AD) of antibiotic-containing biomass. Mesophilic AD was conducted in a completely stirred tank reactor by constantly feeding municipal excess sludge spiked with increasing concentrations of OTC (0–1000 mg L−1) under a solid retention time of 20 days over a period of 265 days. Results showed that methane generation of mesophilic AD was inhibited when the OTC concentration in digested sludge was increased to around 18,000 mg kg−1 (OTC dose, 1000 mg L−1), due to the inhibition of fermenting and acidogenic bacteria. Metagenomic sequencing and high-throughput quantitative PCR analysis demonstrated that tetracycline resistance genes were the most dominant type (38.47–43.76%) in the resistome, with tetG, tetX, tetM, tetR, tetQ, tetO, and tetL as the dominant resistant subtypes throughout the whole experimental period. The relative abundance of these tet genes increased from 2.10 × 10−1 before spiking OTC (OTC concentration in digested sludge, 8.97 mg kg−1) to 2.83 × 10−1 (p < 0.05) after spiking OTC at a dose of 40 mg L−1 (OTC concentration in digested sludge, 528.52 mg kg−1). Furthermore, mobile genetic elements, including integrons, transposons, and plasmids, were also enriched with the increase in OTC dose. Based on partial canonical correspondence analysis, the contributions of horizontal (mobile element alteration) and vertical (bacterial community shift) gene transfer to antibiotic resistome variation were 29.35% and 21.51%, respectively. Thus, considering the inhibition of hydrolytic acidification and enrichment of antibiotic resistome, mesophilic AD is not suggested to directly treat the biomass containing OTC concentration higher than 200 mg L−1.

https://www.sciencedirect.com/science/article/pii/S026974911734589X