鸡粪和猪粪生物发酵过程中抗生素抗性基因的动态变化

畜禽粪便是储存和传播抗生素抗性基因(ARGs)的主要载体.为明确鸡粪和猪粪堆肥过程中ARGs和MGEs相对丰度的变化及影响其消减的关键环境因子，探索减少畜禽粪便堆肥中ARGs含量并降低其污染风险的有效方法，采用实时荧光定量PCR技术和16S rRNA高通量测序技术，测定了鸡粪和猪粪好氧堆肥75 d的过程中，不同阶段10种ARGs和7种可移动遗传元件(MGEs)的丰度变化和细菌群落变化，分析了ARGs和MGEs与细菌群落的相关性和堆体理化性质(温度、含水率、 pH和DOC)变化对ARGs和MGEs丰度的影响.结果表明，猪粪(PM)中ARGs和MGEs丰度显著高于鸡粪(CM).堆肥结束后，两种堆肥中9种ARGs和5种MGEs的相对丰度均显著降低，其中CM中3种ARGs(tetM、tetT和aacA)和4种MGEs(ISEcp1、IS1216、IS613和tnp614)的去除率达到99%; PM中9种ARGstetB(P)、tetL、tetM、tetO、tetT、aacA、aadD、aphA3和sat4]及4种MGEs(ISEcp1、IS26、IS1216和tnp614)去除率均达到99%...

Dynamic Changes in Antibiotic Resistance Genes During Biological Fermentation of Chicken Manure and Pig Manure

Livestock manure is a major carrier that stores and transmits antibiotic resistance genes (ARGs). The aim of this study was to identify the crucial environmental factors that result in the change in relative abundance of ARGs and MGEs to explore effective methods to reduce the occurrence of ARGs. The abundance of ten ARGs and five MGEs were measured using real-time quantitative PCR with 0, 3, 7, 10, 14, 21, 28, 45, 60, and 75 d in CM and PM aerobic composting. The succession law of the bacterial community was analyzed using 16S rRNA high-throughput sequencing. Furthermore, the abundance of ARGs and MGEs was correlated with the properties (temperature, moisture content, pH, and DOC) of composting piles to identify the crucial factors affecting the variation in ARGs and MGEs. The results showed that the abundance of ARGs and MGEs in PM was higher than that in CM. Composting significantly reduced the relative abundance of nine ARGs and five MGEs. The removal ratios of three ARGs (tetM, tetT, and aacA) and four MGEs (ISEcp1, IS1216, IS613, and tnp614) in CM reached 99%. The removal ratios of nine ARGstetB(P), tetL, tetM, tetO, tetT, aacA, aadD,aphA3, and sat4] and four MGEs (ISEcp1, IS26, IS1216, and tnp614) reached 99% in PM. However, the abundance of the genes tetG, intI1, and IS6100 increased. Firmicutes and Actinobacteria were dominant in CM and PM during composting. Actinobacteria and Proteobacteria may have been the major host bacteria of tetG and intI1. The redundancy analysis showed that moisture and pH were the crucial factors that could influence the differences in the abundance of ARGs and MGEs. The composition and abundance of ARGs were driven by physicochemical properties, bacterial community, and MGEs. Composting could significantly reduce the abundance of ARGs in CM and PM, thus reducing the risk of ARGs being distributed via livestock manure application. However, some ARGs and MGEs remained in high abundance. Therefore, it is necessary to further optimize the composting process, improve the harmless treatment effect of livestock manure, and promote the safe agricultural use of organic fertilizers.