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.

这项研究旨在揭示含水量对土壤中四环素抗性基因（TRGs）传播的影响。在实验室条件下，对四种土壤水分含量不同的样品进行了修正，即含水量分别为16％（干土）和25％（湿土），有或没有猪粪。定量聚合酶链反应（q-PCR）结果显示TRG的相对丰度（tet B，tet C，tet M，tet O，tet T和tet无论在施肥还是非施肥条件下，湿土壤中的Z）均显着高于干土壤中的Z）。此外，PM的应用提高了TRG的相对丰度。在湿润土壤中，TRG的绝对拷贝数不会随着16S rRNA基因的减少而下降，这意味着大多数TRG可能位于兼性厌氧细菌中。然而，在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能解释TRGs相对丰度的增加。潮湿土壤中好氧TRB的多样性明显高于干燥土壤，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的群落结构模式与干燥土壤中的不同。