摘要

本研究旨在揭示水分含量对土壤中四环素抗性基因（TRGs）扩散的影响。在实验室条件下对4个土壤含水量不同的样本进行修改，即16％（干土）和25％（湿土），并且有或没有猪粪（PM）。定量聚合酶链式反应（q-PCR）结果表明，无论在受精或非受精条件下，潮湿土壤中TRGs（tetB，tetC，tetM，tetO，tetT和tetZ）的相对丰度均显着高于干燥土壤中的相对丰度受精条件。此外，PM应用增强了TRG的相对丰度。随着湿润土壤中16S rRNA基因的减少，TRGs的绝对拷贝数没有下降，这意味着大多数TRGs可能位于兼性厌氧细菌中。然而，潮湿土壤中可培养的四环素抗性细菌（TRB）与q-PCR结果不一致，进一步表明需氧菌可能不解释TRG相对丰度的增加。有氧TRB在湿地土壤中的分异显着高于干旱土壤，特别是在第14天和第28天。潮湿土壤或含PM的干燥土壤中有氧TRB群落结构的模式与干燥土壤中的不同。总之，这项研究表明，潮湿土壤和干燥土壤之间细菌群落的变化，尤其反映在有氧TRB和/或兼性厌氧TRB群落结构的多样性上，可能是TRG丰度变化背后的重要原因。

This study aimed to reveal the effects of water content on the spread of tetracycline resistance genes (TRGs) in the soil. Amendments of four samples with different soil water contents, namely 16% (dry soil) and 25% (wet soil), and with or without pig manures (PM) were conducted under laboratory conditions. Quantitative polymerase chain reaction (q-PCR) results showed that the relative abundance of TRGs (tetB, tetC, tetM, tetO, tetT, and tetZ) in the wet soils was significantly higher than that in the dry soils whether under fertilization or non-fertilization conditions. Moreover, PM application enhanced the relative abundance of TRGs. The absolute copies of TRGs did not decline with the decrease in 16S rRNA genes in wet soils, implying that most TRGs were probably located in facultative anaerobic bacteria. However, cultivable tetracycline-resistant bacteria (TRB) in the wet soils were not in line with the q-PCR results, further indicating that aerobes might not account for the increases in the relative abundance of TRGs. Diversities of aerobic TRB were significantly higher in the wet soils than in the dry soils, especially on days 14 and 28. The patterns of community structures of aerobic TRB in the wet soils or dry soils containing PM were different from those in the dry soils. Together, this study showed that the variations in bacterial communities between the wet and dry soils, especially reflected in the diversity of aerobic TRB and/or community structure of facultative anaerobic TRB, might be an important reason behind the changes in the abundance of TRGs.

https://www.sciencedirect.com/science/article/pii/S014765131830229X