Performance of full-scale aerobic composting and anaerobic digestion on the changes of antibiotic resistance genes in dairy manure

Abstract

Understanding the different performances of full-scale active composting (AC) and anaerobic digestion (AD) on the changes of antibiotic resistance genes (ARGs) in dairy manure is crucial to uncover the dissemination risks of ARGs in post-biotreated manure. In this regard, metagenomic sequencing was deployed to reveal the variations of ARGs in dairy manure in an intensive dairy farm. Results showed that the total abundance of ARGs increased from 150.64 reads/ng DNA to 204.06 reads/ng DNA in dairy manure, and it is mainly attributed to the contributions of AC (85.49%) rather than AD (14.51%). In AC, more ARG subtypes were induced and the dominant ARG subtypes were shifted completely, probably due to the enrichment of Proteobacteria and Actinobacteria which could be the hosts of multiple ARGs. These results inspire us to further evaluate the dissemination risks of ARGs along the route from composted manure to soil and to plants.