Agriculture and Agri-Food Canada, London Research and Development Centre, London, Ontario, Canada; Department of Biology, University of Western Ontario, London, Ontario, Canada.
Agriculture and Agri-Food Canada, London Research and Development Centre, London, Ontario, Canada.
Sci Total Environ. 2020 Dec 1;746:141113. doi: 10.1016/j.scitotenv.2020.141113. Epub 2020 Jul 24.
We examined the ability of composting to remove ARGs and enteric bacteria in litter obtained from broiler chickens fed with a diet supplemented with Bacitracin methylene disalicylate (BDM) (conventional chicken litter), or an antibiotic-free diet (raised without antibiotic (RWA) chicken litter). This was done by evaluating the litter before and after composting for the abundance of ten gene targets associated with antibiotic resistance or horizontal gene transfer, the composition of the bacterial communities, and the abundance of viable enteric bacteria. The abundance of gene targets was determined by qPCR and the microbial community composition of chicken litter determined by 16S rRNA gene amplicon sequencing. Enteric bacteria were enumerated by viable plate count. A majority of the gene targets were more abundant in conventional than in RWA litter. In both litter types, the absolute abundance of all of the target genes decreased after composting except sul1, intI1, incW and erm(F) that remained stable. Composting significantly reduced the abundance of enteric bacteria, including those carrying antibiotic resistance. The major difference in bacterial community composition between conventional and RWA litter was due to members affiliated to the genus Pseudomonas, which were 28% more abundant in conventional than in RWA litter. Composting favoured the presence of thermophilic bacteria, such as those affiliated with the genus Truepera, but decreased the abundance of those bacterial genera associated with cold-adapted species, such as Carnobacterium, Psychrobacter and Oceanisphaera. The present study shows that chicken litter from broilers fed with a diet supplemented with antibiotic has an increased abundance of some ARGs, even after composting. However, we can conclude that fertilization with composted litter represents a reduced risk of transmission of antibiotic resistance genes and enteric bacteria of poultry origin to soil and crops than will fertilization with raw litter.
我们研究了堆肥去除饲用杆菌肽甲基二磺酸钠（BDM）（常规鸡粪）或无抗生素日粮（无抗鸡粪）饲养的肉鸡粪便中抗生素抗性基因和肠道细菌的能力。通过评估堆肥前后粪便中与抗生素抗性或水平基因转移相关的十个基因靶标丰度、细菌群落组成和可培养肠道细菌丰度来完成。通过 qPCR 确定基因靶标的丰度，通过 16S rRNA 基因扩增子测序确定鸡粪微生物群落组成。通过活菌平板计数计数肠道细菌。与 RWA 鸡粪相比，常规鸡粪中大多数基因靶标更为丰富。在这两种鸡粪类型中，除 sul1、intI1、incW 和 erm(F) 保持稳定外，所有靶基因的绝对丰度在堆肥后均下降。堆肥显著降低了肠道细菌的丰度，包括携带抗生素抗性的细菌。常规鸡粪和 RWA 鸡粪之间细菌群落组成的主要差异归因于假单胞菌属成员，常规鸡粪中该菌属的丰度比 RWA 鸡粪高 28%。堆肥有利于嗜热菌的存在，如与真杆菌属相关的细菌，但减少了与冷适应物种相关的细菌属的丰度，如 Carnobacterium、Psychrobacter 和 Oceanisphaera。本研究表明，饲用抗生素补充日粮饲养的肉鸡粪便中一些 ARGs 的丰度增加，即使经过堆肥也是如此。然而，我们可以得出结论，与使用生鸡粪施肥相比，用堆肥鸡粪施肥代表了降低抗生素抗性基因和家禽来源肠道细菌向土壤和作物传播的风险。
