Potential of novel zinc-based nanomaterials on the microbial community, antibiotic resistance genes, and DNA replication in animal manure

The existence of Antibiotic Resistance Genes (ARGs) in diverse everyday environments, such as animal agriculture, natural surroundings, and waste products, presents potential threats to both human health and food safety. Herein, metagenomic sequencing technique was employed to investigate the impact of two zinc-based nanoparticles, Graphene Oxide-modified Zinc Oxide (GOnZnO) and Microorganism-mediated Zinc Oxide (Micro-ZnO), on the microbial community, ARGs, and DNA replication. The results showed that both GOnZnO and Micro-ZnO significantly reduced zinc levels in animal manure when compared to the control group of nano zinc oxide (nZnO). The order of ARGs copy numbers was nZnO > GOnZnO > Micro-ZnO, with a significant difference between the GOnZnO and Micro-ZnO groups. Additionally, the expression levels of various DNA replication genes, including DNA polymerase III holoenzyme, dnaB, dnaG, RNeseH, polA, and Lig, were significantly lower in the GOnZnO group compared to the nZnO group. The Micro-ZnO group exhibited even lower expression levels of these genes compared to the GOnZnO group. In contrast, GOnZnO and Micro-ZnO had no significant impact on archaeal DNA replication pathway-related genes. Specifically, the expression of RNASEH1 was significantly higher in the Micro-ZnO group compared to the GOnZnO and nZnO groups. Co-occurrence network analysis revealed changes in ARGs driven by bacterial and eukaryotic DNA replication and microbial community dynamics. However, there was no correlation observed between ARGs and archaeal DNA replication genes. Overall, these findings add to the existing literature regarding the application of GOnZnO and Micro-ZnO as potential agents for reducing ARGs pollution.