Microbial Diversity and Heavy Metal Resistome in Slag-Contaminated Soils from an Abandoned Smelter in Chihuahua, Mexico

Heavy metal(loid) (HM) contamination in soils from smelting activities poses significant environmental and public health risks, as well as disruptions in microbial community dynamics and HM resistance gene profiles. This study investigates the microbial diversity, resistome, and physicochemical properties of soils from the abandoned Avalos smelter in Chihuahua, Mexico. Through soil analyses, we identified elevated concentrations of certain HMs, which pose serious environmental and health hazards. The metagenomic analysis of the microbial community, composed of bacteria, archaea, and fungi, was dominated by genera such as Streptomyces, Bradyrhizobium, Halobaculum, Nitrosocosmicus, Fusarium, and Aspergillus in rhizospheric soil. Furthermore, a diverse array of metal resistance genes (MRGs) were detected, associated with copper, arsenic, iron, lead, cadmium, zinc, and other HMs. Additionally, metagenome-assembled genomes (MAGs) revealed the presence of functional genes linked to HM resistance, providing deeper insights into the ecological roles and metabolic capabilities of microbial taxa. These findings highlight the significant impact of smelting-derived contamination on microbial diversity and functional potential, offering valuable insights for the development of bioremediation strategies in HM-contaminated environments.