Public risk of sewage sediments in different functional areas - deciphered by metagenome assembly

Understanding public risk of sewage sediments, particularly those risks related to methane, sulfide emission and bio-risk, is critical for ensuring citizen safety. However, the underlying microbial mechanisms causing these risks remain unclear. This study employed metagenomic assembly to analyze methane/sulfur cycling pathways and bio-risks in sewage sediments from three typical functional areas: commercial, multifunctional, and residential. Results demonstrated that the sewage sediments in the multifunctional area exhibited the highest potential public risk levels, characterized by intensified methane/sulfur metabolic activity and increased abundance of mobile gene elements (MGEs) and high-risk antibiotic resistance genes (ARGs). In addition, the co-occurrence network complexity of ARGs, MGEs and pathogens were higher in the multifunctional sewage sediments. Intriguingly, we found genus Thiobacillus which participated in sulfur cycling, as the host of high risk ARGs, significantly enriched in the multifunctional area, also distributed in sewer systems around the world. Additionally, total organic carbon (TOC) emerged as key driver of sediment public risks. These findings highlight variations in sewage sediment public risks across different functional areas, providing a foundation for targeted risk mitigation strategies.