摘要

堆肥是城市污水污泥回收利用的广泛用法，可以改善土壤，也是将抗生素抗性细菌和抗生素抗性基因传播到土壤的潜在途径。然而，污泥堆肥过程中抗生素抗性基因（ARGs）的动态变化和内在机制尚未得到充分探索。在这里，我们使用高通量定量PCR和16S rRNA基因的Illumina测序来研究污泥在室内堆肥过程中ARGs和细菌群落的动态变化。检测到堆肥过程中156种独特的ARG和移动遗传元件（MGE），它们几乎编码所有主要类别的抗生素抗性。结果表明，堆肥过程中ARGs丰度和多样性显着提高，形态明显，且富集。堆肥过程中细菌群落结构和组成发生明显变化，后期以放线菌为主。放线菌的大量增殖可能是堆肥期间ARG的增加的原因。 ARGs模式与细菌群落结构显着相关，表明堆肥过程中ARGs的动态受到细菌系统发育成分的强烈影响。这些结果意味着直接施用污泥堆肥可能会导致大量的ARG在土壤中蔓延。

Composting is widely used for recycling of urban sewage sludge to improve soil properties, which represents a potential pathway of spreading antibiotic resistant bacteria and genes to soils. However, the dynamics of antibiotic resistance genes (ARGs) and the underlying mechanisms during sewage sludge composting were not fully explored. Here, we used high-throughput quantitative PCR and 16S rRNA gene based illumina sequencing to investigate the dynamics of ARGs and bacterial communities during a lab-scale in-vessel composting of sewage sludge. A total of 156 unique ARGs and mobile genetic elements (MGEs) were detected encoding resistance to almost all major classes of antibiotics. ARGs were detected with significantly increased abundance and diversity, and distinct patterns, and were enriched during composting. Marked shifts in bacterial community structures and compositions were observed during composting, with Actinobacteria being the dominant phylum at the late phase of composting. The large proportion of Actinobacteria may partially explain the increase of ARGs during composting. ARGs patterns were significantly correlated with bacterial community structures, suggesting that the dynamic of ARGs was strongly affected by bacterial phylogenetic compositions during composting. These results imply that direct application of sewage sludge compost on field may lead to the spread of abundant ARGs in soils.

http://pubs.acs.org/doi/abs/10.1021/acs.est.5b01012