Dissolved organic matter fosters core mercury-methylating microbiomes for methylmercury production in paddy soils

作者：Qiang Pu, Bo Meng, Jen‐How Huang, Kun Zhang, Jiang Liu, Yu‐Rong Liu, Mahmoud A. Abdelhafiz, Xinbin Feng · 发表于：Biogeosciences · 年份：2025 · DOI：10.5194/bg-22-1543-2025 · 被引用次数：18 · 研究领域：Mercury impact and mitigation studies

Abstract. Methylmercury (MeHg), accumulated in rice grains, is highly toxic for humans. Its production is largely driven by microbial methylation in paddy soils; however, dissolved organic matter (DOM) is a critical component of the soil biogeochemistry process, yet its interactions with microorganisms involved in MeHg production remain poorly understood. Here, we conducted hgcA gene sequencing and a genome-resolved metagenomic analysis to identify core Hg-methylating microbiomes and investigate the effect of DOM on core Hg-methylating microbiomes in paddy soils across a Hg contamination gradient. In general, the Hg-methylating microbial communities varied largely with the degree of Hg contamination in soils. Surprisingly, a core Hg-methylating microbiome was identified that was exclusively associated with MeHg concentration. The partial Mantel test revealed strong linkages among core Hg-methylating microbiome composition, DOM, and MeHg concentration. Structural equation models further indicated that core Hg-methylating microbiome composition significantly impacted soil MeHg concentration, contributing 89 % of the observed variation, while DOM plays a crucial role in determining core Hg-methylating microbiome composition, accounting for 65 %. These results suggested that DOM regulates MeHg production by altering the composition of core Hg-methylating microbiomes. The presence of various genes associated with carbon metabolism in the metagenome-assembled genome of core Hg-meth...