摘要

有机肥料是储存和传递抗生素抗性基因（ARGs）的主要载体。在环境中，由于有机肥在农业上的应用，ARGs的多样性和丰度不断增加，对人类健康和环境安全构成潜在威胁。本文研究了堆肥处理不同类型有机肥的微生物群落结构和ARGs。结果表明，蚯蚓粪有机肥中ARGs含量最低，鸡粪有机肥中ARGs含量最高。有趣的是，有机肥料中ARGs的丰度和多样性，特别是β-内酰胺抗性基因、磺胺抗性基因和大环内酯-林可酰胺-链霉素B（MLSB）抗性基因的丰度和多样性显著降低，而堆肥对可移动基因元件（MGEs）的影响不显著，其中抗生素失活和利用外排泵是两个最主要的机制。很明显，随着细菌数量和潜在ARG宿主多样性的减少，ARGs的去除变得更加有效，整合子介导的水平基因转移（HGTs）在大多数ARG类型的扩散中发挥了重要作用。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驱动的。此外，通过对一些特性、抗生素残留量、微生物群落结构和ARGs的相关分析表明，堆肥理化性质对细菌群落的多样性和丰富度的影响是形成和改变ARGs丰富度和多样性的主要驱动因素，而不是HGT。一般来说，高温堆肥能有效地去除有机肥料中的抗生素残留和ARGs，但不能阻止MGEs的扩散。从这些结果中获得的见解可以通过指示堆肥处理后不同类型有机肥中微生物群落结构和ARGs的变化，为有机肥的安全合理使用提供帮助。

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