牛粪堆肥系统环境因子对抗性基因的影响

本研究利用实时定量PCR技术检测牛粪60 d好氧堆肥过程中典型四环素类抗性基因(tet Q、tet W、tet M、tet G、tet A和tet X)和大环内酯类抗性基因(erm35、erm36、erm B、erm F、erm T和erm X)的数量变化规律,系统研究了温度、含水率、挥发性有机质(VS)含量、碳氮比(C/N)、pH值、氧化还原电位(ORP)等堆肥系统环境因子和细菌数量(TCB)对这两类典型抗生素抗性基因的影响.结果表明,堆肥升温阶段牛粪中tet Q、tet W、tet G和tet X数量分别增加1. 7、0. 3、84. 8和4. 5倍,而tet M丰度降低了83. 1%;堆肥腐熟阶段牛粪中tet G和tet X数量分别增加23. 8和11. 5倍,而tet W、tet Q和tet M数量均降低90%.整个牛粪堆肥过程中erm35、erm36、erm B、erm F、erm T和erm X丰度分别增加2. 1、430. 4、0. 6、11. 5、2. 1和49. 1倍. RDA分析表明,牛粪堆肥过程中对四环素与大环内酯类抗性基因数量影响较大的3个环境因子分别为:ORP(54. 8%)、温度(34%)和VS(11. 3%),其中ORP与erm X和erm B、温度与tet Q和erm F以及VS与tet W数量均呈明显地正相关.

Effects of Environmental Factors on Tetracycline and Macrolides Resistance Genes in Cattle Manure Composting Systems

The effects of environmental factors and bacterial numbers on typical tetracycline resistance genes (tetQ, tetW, tetM, tetG, tetA, and tetX) and macrolide resistance genes (erm35, erm36, ermB, ermF, ermT, and ermX) during cow manure composting were investigated and quantified via real-time quantitative PCR. The results suggested that the abundance of tetQ, tetW, tetG, and tetX increased by 1.7, 0.3, 84.8, and 4.5 times respectively, whereas tetM decreased by 83.1% during the heating stages of cow manure composting. The abundance of tetG and tetX increased by 23.8 and 11.5 times respectively, whereas tetW, tetQ, and tetM decreased by 90% during the maturity stage. However, the macrolide resistance genes (erm35, erm36, ermB, ermF, ermT, and ermX) increased by 2.1, 430.4, 0.6, 11.5, 2.1, and 49.1 times, respectively. Redundancy analysis showed that ORP, temperature, and VS were crucial factors that could explain the variations of 54.8%, 34%, and 11.3%, respectively, in ARGs. ORP, temperature, and VS also had the greatest positive correlation with ermX, ermB, tetQ, ermF, and tetW, in that order.