Study on the effect of straw addition ratio on antibiotic resistance genes in rapid production of cattle manure organic fertilizer

The substances in ecosystems flow along the food chain. Therefore, we should establish a monitoring system for antibiotic resistance genes (ARGs) in fertilizer products as soon as possible to regulate the use of fertilizers. In this study, three groups of cattle manure organic fertilizers were set up according to the ratio of straw addition, namely CK: cattle manure: straw = 6:4; M1: cattle manure = 100%; M2: cattle manure: straw = 8:2. All groups were supplemented with microbial agents. Their effects on ARGs, class 1 integron integrase genes (intI1) and bacterial communities were investigated. At the end of composting, the relative abundance of sul1, sul2, tetG, and intI1 in M1 and M2 were significantly lower than that in the CK group, and most of the ARGs in each group were removed. The changes in the relative abundance of ARGs are related to changes in microbial community structure. The establishment of temperature conditions is a key factor affecting the structure of microbial communities. Bacillus may play an important role in controlling the relative abundance of ARGs. We found that the most suitable ratio of cattle manure to straw was 8:2 among the three groups, which not only ensured the balanced nutritional composition of organic fertilizers, but also effectively reduced the abundance of ARGs.