高温持续时间对鸡粪堆肥中多重耐药菌、接合型质粒及耐药基因消减特征的影响

为研究堆肥过程中高温持续时间对多重耐药大肠杆菌及其携带的接合型质粒和抗生素耐药基因（Antibiotic resistance gene,ARGs）消减规律的影响，本研究在鸡粪堆肥初始物料中外源添加多重耐药大肠杆菌菌液，并设置延长高温时间组（CT组）和常规堆肥组（NT组）两种堆肥条件处理，利用选择性培养及16S rRNA基因扩增子测序技术检测多重耐药菌群变化规律，同时利用数字PCR定量检测大肠杆菌16S rRNA基因、接合型质粒转移酶基因（MOBP）、氨基糖苷类耐药基因APH(3)-Ib]及磺胺类耐药基因（sul2）和Ⅰ类整合子-整合酶基因（intl1）等污染物相对丰度变化，对比获得了延长高温时间对多重耐药菌及其ARGs消减速率的影响。结果表明，高温堆肥能够明显抑制堆肥中多重耐药菌的生长，并且CT组对其的抑制效果明显好于NT组。堆肥结束后，五种基因在CT组的相对丰度消减率为79.82%～99.99%，但NT组中腐熟期结束后APH(3)-Ib、sul2、intl1等基因相对丰度均高于初始物料。多重耐药大肠杆菌及其接合型质粒的消减规律均符合一级动力学方程，但APH(3)-Ib、sul2和...

Effects of continuous thermophilic phase on removal of multidrug-resistant bacteria, its conjugative plasmids and antibiotic resistance genes during chicken-manure composting

To investigate the effect of continuous thermophilic phase on multidrug-resistant(MDR) Escherichia coli, its conjugative plasmid, and its antibiotic resistance genes(ARGs)during composting, MDR E. coli was inoculated into chicken-manure-composting raw material. Two treatments, namely normal thermophilic(NT) and continuous thermophilic(CT) composting treatments, were set up. Selective cultivation of MDR bacteria and 16S rRNA gene amplicon sequencing were used to monitor the variations in MDR bacteria. Digital droplet PCR was used to quantify the relative abundance of 16S rRNA genes of E. coli, namely the mobility proteins(MOBP), aminoglycoside resistance gene(APH(3) -Ib), sulfonamide resistance gene(sul2), and class I integrase gene(intl1). The effects of the CT treatment on MDR bacteria and the ARG reduction rate were obtained by comparison. According to the results, high-temperature composting could inhibit MDR bacteria growth significantly, and the inhibitory effect of the CT treatment was superior to that of the NT treatment. After composting, the reduction rate of the five detected genes in CT treatment was from 79.82% to 99.99%, however, the relative abundance of APH(3)-Ib, sul2, intl1 in NT treatment after ripening period was greater than that in the raw material. Reduction kinetics analysis of ARGs showed that the reduction of MDR E. coli and its conjugative plasmids conformed to the first-order reaction kinetics; however, the reduction kinetics of APH(3)- Ib, sul2, and intl1 showed obvious two -stage characteristics. Prolonging the thermophilic phase could inhibit the rebound of ARGs(CT treatment)significantly and restrain the rebound in the maturing period. Finally, shifts in bacterial community structure during composting were analyzed. The increase in relative abundance of ARGs in the NT treatment was related to the enrichment of specific genera, such as Moheibacter and Halomonas. The results show that during composting, prolonging the thermophilic phase could reduce the abundance of bacteria, which could be potential hosts to drug resistance genes; inhibit the vertical transmission of ARGs; and finally reduce ARG abundance in the finished fertilizer.