摘要
      有机肥料增加抗生素抗性基因（ARGs）和细菌病原体已被广泛记录。然而，长期（≥5年）施用有机肥后，有机肥如何参与改变土壤ARG和致病菌仍不清楚。本文比较了有机施肥土壤（AF）和非施肥土壤（NF）中的ARGs和致病菌，并确定了输入源（有机肥、灌溉水、空气和背景土壤）对土壤ARGs的贡献。结果表明，房颤中某些ARGs的丰度，如vanR和aac（6′）-I，显著高于NF（p＜0.05）。房颤中潜在病原体的丰度相对较高，尤其是肠炎沙门氏菌和嗜麦芽窄食单胞菌。这表明施用有机肥可以使一些土壤ARGs和致病菌保持高水平至少5年。可追溯性分析发现，施用有机肥主要增加了其自身对土壤ARG的贡献，从1.16%增加到9.05%，并减少了背景土壤的贡献，这表明土壤ARG增加的部分原因可能是有机肥投入。值得注意的是，施用有机肥并没有显著改变输入源对微生物的贡献率，但土壤微生物的组成发生了明显变化，这意味着输入源对土壤微生物的影响可能来自其他因素，而不是直接输入。随后的结构方程表明，施用有机肥显著增强了环境因素对ARGs的影响，也间接增加了群落对ARGs。总的来说，在长期施肥的情况下，有机肥料对土壤ARGs的作用不仅来源于其自身的投入，而且主导着环境因素对ARGs影响。本研究阐明了AF与NF中ARGs差异的主要原因，并对有机肥料在其中的实际作用有所启示。
Abstract
Organic fertilizer increase antibiotic resistance genes (ARGs) and bacterial pathogens have widely documented. However, how organic fertilizer is involved in changing soil ARGs and pathogenic bacteria after long-term (≥5 years) application remains unclear. Herein, the ARGs and pathogenic bacteria were compared in organic fertilized soils (AF) and non-fertilized soils (NF), and the contribution of input sources (organic fertilizer, irrigation water, air and background soil) on soil ARGs also was determined in this study. Results showed that the abundances of some ARGs, such as vanR and aac(6′)-I in AF, were significantly higher than these of NF (p < 0.05). And a relatively higher abundance of potential pathogens, especially, Salmonella enterica and Stenotrophomonas maltophilia, in AF was observed. This indicated that organic fertilizer application can maintain a high level of some soil ARGs and pathogenic bacteria for at least 5 years. Traceability analysis unearthed that organic fertilizer application mainly increased its own contribution to soil ARGs from 1.16% to 9.05%, as well reduced the contribution of background soil, suggesting that the increase in soil ARGs may be partly attributable to organic fertilizer inputs. Notably, organic fertilizer application did not significantly alter the contribution ratio of input sources to microorganisms, but there was a clear change in the composition of soil microorganisms, which meant that the effect of the input source on the microorganism may emanate from other factors, rather than direct inputs. Subsequent structural equation demonstrated that organic fertilizer application significantly enhanced the effect of environmental factors on ARGs, and also indirectly increased the influence of communities on ARGs. Collectively, under the long-term fertilization, the role of organic fertilizers on soil ARGs not just stems from its own input, and also dominates the influence of environmental factors on ARGs. This study elucidates main causes for the difference in ARGs in AF vs. NF and enlightens actual role of organic fertilizer in them.

https://www.sciencedirect.com/science/article/abs/pii/S0301479722009550