show Abstracthide AbstractMercury (Hg) methylation is a bio-mediated process that produces methylmercury (MeHg), a neurotoxin that accumulates in global food webs. Two highly conserved genes hgcA and hgcB, are required in Hg methylation, which provides a basis for evaluating the distribution patterns of Hg methylators in different environments. However, the hgcA diversity and distribution of Hg methylators in freshwater and seawater sediments remain poorly understood. In this study, we conducted a large-scale omics analysis to identify distribution patterns of Hg methylators.