摘要

      施用氟苯尼考对土壤抗药性和氮素循环有影响，但其相互作用尚未完全阐明。本研究采用实时荧光定量PCR（qPCR）和亚基因组测序技术，在短期（30d）土壤模型试验中，对土壤细菌的抗生素抗性基因（ARGs）和氮循环基因进行了研究。氟苯尼考显著改变了氨基糖苷类、β-内酰胺类、四环素类和大环内酯类耐药基因的丰度。氟苯尼考对鞘氨酯单胞菌科的丰度、蛋白质代谢和氮代谢功能以及NO还原酶、硝酸还原酶、亚硝酸盐还原酶和N2O还原酶也有影响。因此，ARG类基因对氨基糖苷类、β-内酰胺酶、四环素类、沾菌素类、磷霉素、氯霉素和甲氧苄氨嘧啶的抗性与多个氮循环基因密切相关。放线菌、绿菌、厚壁菌、芽单胞菌、硝化螺旋菌、变形菌和疣微菌在ARGs的传播中起着重要作用。此外，土壤理化性质是影响土壤植物区系分布的重要因素。本研究为进一步探讨ARGs在土壤氮素循环中的传播规律和干扰机理提供了理论依据。

      Soil antibiotic resistome and the nitrogen cycle are affected by florfenicol addition to manured soils but their interactions have not been fully described. In the present study, antibiotic resistance genes (ARGs) and nitrogen cycle genes possessed by soil bacteria were characterized using real-time fluorescence quantification PCR (qPCR) and metagenomic sequencing in a short-term (30 d) soil model experiment. Florfenicol significantly changed in the abundance of genes conferring resistance to aminoglycosides, β-lactams, tetracyclines and macrolides. And the abundance of Sphingomonadaceae, the protein metabolic and nitrogen metabolic functions, as well as NO reductase, nitrate reductase, nitrite reductase and N₂O reductase can also be affected by florfenicol. In this way, ARG types of genes conferring resistance to aminoglycosides, β-lactamases, tetracyclines, colistin, fosfomycin, phenicols and trimethoprim were closely associated with multiple nitrogen cycle genes. Actinobacteria, Chlorobi, Firmicutes, Gemmatimonadetes, Nitrospirae, Proteobacteria and Verrucomicrobia played an important role in spreading of ARGs. Moreover, soil physicochemical properties were important factors affecting the distribution of soil flora. This study provides a theoretical basis for further exploration of the transmission regularity and interference mechanism of ARGs in soil bacteria responsible for nitrogen cycle.

     https://www.sciencedirect.com/science/article/pii/S0269749119349012