摘要

    有机肥料是存储和传播抗生素抗性基因（ARG）的主要载体。在环境中，由于有机肥料在农业中的应用，ARG的多样性和丰富性不断增加，对人类健康和环境安全构成了潜在威胁。本文研究了堆肥处理后不同类型有机肥的微生物群落结构和ARGs。我们发现，cast粪有机肥中ARGs的丰度和多样性最低，而鸡粪有机肥中ARGs的最低和最高。有趣的是，有机肥料中ARG的丰富度和多样性，特别是β-内酰胺抗性基因，磺酰胺抗性基因和大环内酯-林可酰胺-链霉菌素B（MLSB）抗性基因显着减少，而堆肥不会引起移动遗传元素的显着变化（MGEs），其中抗生素失活和使用外排泵是两个最主要的机制。显然，随着细菌丰度的降低和潜在ARG宿主多样性的增加，去除ARG变得更加有效，整合子介导的水平基因转移（HGT）在大多数ARG类型的增殖中起着重要作用。因此，ARGs的减少主要是由堆肥引起的细菌群落组成的变化所致。此外，受堆肥物理和化学特性影响的细菌群落的多样性和丰富度，而不是HGT，是塑造和改变ARGs的丰富度和多样性的主要驱动力，这些性质，抗生素残留，微生物群落之间的相关性分析表明了这一点。结构和ARG。通常，高温堆肥可以有效地从这些有机肥料中去除抗生素残留物和ARG。但是，它不能阻止MGE的扩散。从这些结果中获得的见解可能通过指出堆肥处理的不同类型有机肥料中微生物群落结构和ARGs的变化，有助于安全合理地使用有机肥料。

    Organic fertilizer is a major carrier that stores and transmits antibiotic resistance genes (ARGs). In the environment, due to the application of organic fertilizers in agriculture, the increasing diversity and abundance of ARGs poses a potential threat to human health and environmental safety. In this paper, the microbial community structure and ARGs in different types of organic fertilizer treated with composting were examined. We found that the abundance and diversity of ARGs in earthworm cast organic fertilizer were the lowest and the highest in chicken manure organic fertilizer. Interestingly, the abundance and diversity of ARGs, especially beta-lactam resistance genes, sulfonamide resistance genes, and macrolide-lincosamide-streptogramin B (MLSB) resistance genes, in organic fertilizers were reduced significantly, while composting caused no significant change in mobile genetic elements (MGEs), where antibiotic deactivation and the use of efflux pumps were the two most dominant mechanisms. It was clear that removal of ARGs became more efficient with increasing reduction in the bacterial abundances and diversity of potential ARG hosts, and integron-mediated horizontal gene transfers (HGTs) played an important role in the proliferation of most ARG types. Therefore, the reduction in ARGs was mainly driven by changes in bacterial community composition caused by composting. Furthermore, rather than HGTs, the diversity and abundance of bacterial communities affected by compost physical and chemical properties were the main drivers shaping and altering the abundance and diversity of ARGs, which was indicated by a correlation analysis of these properties, antibiotic residues, microbial community structure, and ARGs. In general, high-temperature composting effectively removed antibiotic residues and ARGs from these organic fertilizers; however, it cannot prevent the proliferation of MGEs. The insights gained from these results may be of assistance in the safe and rational use of organic fertilizers by indicating the changes in microbial community structure and ARGs in different types of organic fertilizer treated with composting.

    https://www.mdpi.com/2076-2607/8/2/268