Vermicomposting reduces the antimicrobial resistance in livestock waste

Abstract

Vermicomposting, a process in which housefly larvae are used to decompose organic waste, has attracted attention as a method for managing antimicrobial-resistant bacteria (ARB) in livestock manure. Vermicomposting effectively reduces antimicrobial resistance genes (ARGs) and residual antimicrobials. However, the evaluation of live bacteria, including ARB, remains scarce. Additionally, conventional DNA extraction methods include DNA from dead bacteria, impeding the accurate evaluation of ARG-associated risk in compost and the microbiome. This study assesses the effectiveness of vermicomposting pig manure against antimicrobial resistance (AMR) by evaluating the ARB, ARGs (focusing on DNA from live bacteria), and microbiome associated with vermicomposting processes. Vermicomposting significantly reduces the abundance of bacteria, including ARB, and decreases the ARG (tetA, tetB, bla_TEM, and bla_CTX−M) copy number in live bacteria. Bacterial community analysis revealed an increase in the abundance of Gammaproteobacteria. Moreover, the vermicomposted samples effectively cultivated myriad plants. Overall, vermicomposting effectively reduces the ARB and ARGs in pig manure, with potential benefits for plant growth and sustainable waste management. Hence, it can be widely applied to treat livestock manure and other organic wastes to combat AMR.