摘要
      在本研究中，评估了在猪粪厌氧消化（AD）过程中添加纳米Fe2O3（NF）后，不同暴露时间（ET）下抗生素抗性基因（ARGs）甲烷产生和命运的双重特征。NF对甲烷的产生有抑制作用，其抑制作用与剂量成正比。当ET为30天时，由于细胞完整性的破坏和对细菌群落的破坏，NF350使累积甲烷产量减少了约7.8%。尽管如此，当ET短于12天时，NF可以将最大比甲烷产生率提高24.5%。在此阶段，ARGs相对丰度的变化与每日甲烷产量成正比。短时间内添加NF有助于产甲烷活性，这可能与种间直接电子转移（DIET）有关。当ET为30天时，NF特异性地增强了具有抗生素靶向保护的四环素抗性基因（40.7%）和具有抗生素失活的氨基糖苷类抗性基因（34.0%）的减少。据推测，特异性降低主要是由于较高的NF可以产生ROS（活性氧），通过抗生素失活下调磷酸化、乙酰化和珠颈酰化的关键酶作用，并降低四环素的选择性压力降低。通过结构方程模型（SEM）和Procrustes分析，环境变量和微生物群落是导致ARGs变化的主要因素。这些结果表明，合理添加NF有助于提高猪粪AD过程中的累积甲烷产量并减少ARGs。
Abstract
In this study, the dual character of the methane production and fate of antibiotic resistance genes (ARGs) were evaluated after adding nano-Fe2O3 (NF) during anaerobic digestion (AD) of swine manure, concerning the different exposure times (ET). NF has a decreasing effect on methane production, and the inhibitory effect is proportional to the dosage. NF350 decreased the accumulative methane production by about 7.8% when the ET was 30 days due to the disruption of cellular integrity and the damage to the bacterial communities. Nonetheless, NF could improve the maximum specific methane production rate by up to 24.5% when the ET was shorter than 12 days. And the changes in the relative abundance of ARGs were proportional to the daily methane production at this stage. The addition of NF in a short time is helpful for methanogenic activities, which might be correlated with direct interspecies electron transfer (DIET). NF specifically enhanced the reduction of tetracycline resistance genes with antibiotic target protection (40.7%) and aminoglycoside resistance genes with antibiotic inactivation (34.0%) when the ET was 30 days. It was speculated that the specifical reduction was mainly due to that higher NF could produce the ROS (reactive oxygen species), down regulate key enzyme actions in phosphorylation, acetylization, and nucelotidylalation with antibiotic inactivation, and reduces the reduction of selective pressure for tetracycline. Environmental variables and microbial community were the major factors causing the changes of the ARGs by Structural equation models (SEM) and Procrustes analysis. These results illustrated that resonable NF addition could help to improve the accumulative methane production and reduce ARGs during AD of swine manure.

https://www.sciencedirect.com/science/article/abs/pii/S0959652622038124