Abstract:
In order to investigate the effect of pile-turning interval on ARGs and MGEs in continuous composting of ectopic fermentation bed , two conditions of turning over once 1 d (F1 group) and 2 d turning once (F2 group) were set. Fifteen target genes, including 2 tetracycline (tetG, tetW), 3 sulfonamide (sul1,sul2,dfrA1), 2 β-lactamse (blaTEM-1,fexA), 2 MLSB (ermX, ermQ), 2 FCA (optrA, IsaE) and 1 aminoglycoside (aac(6?)-Ib-cr),1 integrase (intI1) and 2 transposon (Tn916/1545, ISCRI) genes, were identified by PCR in composting process; while 7 genes with high detection rate (tetG, tetW, sul1, sul2, blaTEM-1, ermQ, intI1) were quantitatively detected by qPCR. The PCR results showed that, 11 kinds of ARGs (tetG, tetW, sul1, sul2, blaTME-1, fexA, ermX, ermQ, optrA, IsaE, aac (6?)-Ib-cr) and 3 kinds of MGEs (intI1, Tn916/1545, ISCRI) were detected in both groups, in which the detection rates of 7 genes (tetG, tetW, sul1, sul2, blaTME-1, ermQ、intI1) were higher; 12 species from 0 to 5 d, 1 species at 33 d in F1 and 40 d in F2, increased significantly after 40 d, indicating that the species of ARGs and MGEs changed with the change of temperature. qPCR results showed that the total relative abundance of 7 target genes in both groups show a trend from rise to decline during the experiment, at the end,decreased by 82.33% and 78.89% compared with 0 d in F1 and F2, respectively; among which the relative abundance of tetG、tetW、sul1、blaTEM-1、ermQ and intI1 was decreased by 16.51%、87.89%、54.58%、>99.99%、97.80%、59.29% and 64.32%、99.46%、50.91%、99.29%、82.22%、99.92%. The results showed that the types and relative abundance of ARGs reduced during degradation manure and sewage at high temperature period in ectopic fermentation bed, and the removal efficiency of most ARGs was better by turned over once every two days.