Relative abundance of heavy metal resistance genes of three drinking water treatment plants unveiled through shotgun metagenomics

Introduction: The occurrence and abundance of heavy metal resistance genes (HMRGs) in drinking water treatment plants (DWTPs) and the stages at which they occur are a global challenge due to the risk of consuming contaminated water. Methods: The present study identified HMRGs associated with raw water sources, treatment stages (disinfection and filtration), final treated water, and produced sludge in three DWTPs across three provinces (Gauteng, Limpopo, and Mpumalanga) in South Africa, using a shotgun metagenomic approach. Results: In total, five classes of heavy metals (copper, arsenic, mercury, chromate, silver) and 50 resistance genes were identified across the three DWTPs. Most of the genes were obtained from the disinfection stages of the DWTPs. Discussion: This genomic dataset provides valuable information on the impact of disinfection stages on the relative abundance of HMRGs in drinking water treatment processes. Additionally, the transfer of genes into the final treated water consumed by the populace is a significant human health concern.