How Does Vegetable Waste Decomposition Influence the Antibiotic Resistome and the Human Bacterial Pathogen Structure in Leachates?

Abstract

Understanding how antibiotic-resistance genes (ARGs) and pathogens in household waste leachates contribute to acquiring antibiotic resistance is profoundly significant. Leachates can impair water quality and harm the environment and human health. This study explored co-occurrence and accumulation of pathogens and ARGs in leachates during decomposition of vegetable wastes. Watercress leachates had more average ARG numbers and abundance. ARG abundances were 2.17 × 107 copies/mL for pepper, 1.27 × 107 copies/mL for watercress, and 4.93 × 105 copies/mL for onion. Vegetable decomposition enriched ARGs first and then decreased. Genes conferring resistance to multidrug, aminoglycosides, and β-lactam were the dominant ARGs; the main mechanism was antibiotic deactivation. Preferential co-occurrence patterns were observed across ARG types, indicating coeffects of antibiotic selection pressure and coresistance when shaping the antibiotic resistome. The pathogenic community varied significantly during vegetable decomposition. ARG levels positively correlated with the dominant Enterococcus but negatively correlated with Bartonella and Bacteroides. Functional genes shared by all waste leachates were mainly linked to carbohydrate (9.2%) and amino acid transport and metabolism (8.2%). ARGs were positively associated with defensive virulence factors and autoinducers. The quorum sensing system regulated ARG levels by balancing signal molecule synthesis and degradation gene expression. These findings provide insights into the mechanism underlining vegetable waste decomposition regarding occurrence and spread of ARGs in leachates.