[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.