摘要

在22年的田间试验的三个不同土壤样品中，对15种抗生素抗性基因（ARGs）和intI1（涉及ARGs水平基因转移（HGT）的基因）进行了定量，这些样品已接受无机肥料（NPK），有机肥料（OM） ；小麦秸秆，大豆油饼和棉饼的混合物，以及未施肥和肥料（CK）的对照田。 Tet（L）是OM中最丰富的ARG，其中也包含相当水平的intI1。对过去22年中每年收集的存档土壤进行的分子分析表明，OM土壤中的tet（L）和intI1高于NPK土壤。在这些年中，tet（L）的相对丰度基本保持不变，而OM土壤中的intI1水平则随着时间而下降。在存档的和新鲜土壤，OM和灌溉水中，tet（L）的主要基因型相同。对四环素抗性细菌（TRB）分离物的16S rRNA基因进行系统进化分析表明，OM中带有tet（L）的Firmucutes与OM土壤中的相似，表明OM将TRB转移到了它们存活的OM土壤中。从OM分离出的几乎所有TRB都带有tet（L）并属于Firmicutes。携带tet（L）的有机肥料中细菌的存活可能是OM土壤中tet（L）水平升高的原因。

Fifteen antibiotic resistance genes (ARGs) and intI1, a gene involved in horizontal gene transfer (HGT) of ARGs, were quantified in three different soil samples from a 22 year old field experiment that had received inorganic fertilizer (NPK), organic manure (OM; a mixture of wheat straw, soybean oil cake and cotton cake), and control fields that had received no fertilizer and manure (CK). Tet(L) was the most abundant ARG in OM, which also contained considerable levels of intI1. Molecular analysis of yearly collected archived soils over the past 22 years showed that tet(L) and intI1 were higher in OM soils than in NPK soils. The relative abundance of tet(L) was essentially constant during these years, while the level of intI1 in OM soils decreased over time. The main genotype of tet(L) was the same in archived and in fresh soil, OM, and irrigation water. Phylogenetic analysis of the 16S rRNA genes of tetracycline-resistant bacteria (TRB) isolates indicated that the Firmucutes carrying tet(L) in OM were similar to those in the OM soil, suggesting that OM transferred TRB into the OM soils where they survived. Almost all of the TRB isolated from OM carried tet(L) and belonged to the Firmicutes. Survival of bacteria from the organic manure that carried tet(L) may be the cause of the increased level of tet(L) in OM soil.

https://www.frontiersin.org/articles/10.3389/fmicb.2018.01140/full