Distribution and Environmental Preference of Potential Mercury Methylators in Paddy Soils across China.

The neurotoxin methylmercury (MeHg) is produced mainly from the transformation of inorganic Hg by microorganisms carrying the gene pair. Paddy soils are known to harbor diverse microbial communities exhibiting varying abilities in methylating inorganic Hg, but their distribution and environmental drivers remain unknown at a large spatial scale. Using gene amplicon sequencing, this study examined Hg-methylating communities from major rice-producing paddy soils across a transect of ∼3600 km and an altitude of ∼1300 m in China. Results showed that OTU richness was higher in tropical and subtropical paddy soils compared to temperate zones. , , and were identified as the dominant families associated with MeHg production, collectively accounting for up to 77% of total sequences. Hierarchical partitioning analyses revealed that pH was the main driver of genes from (14.8%) and (16.3%), while altitude accounted for 21.4% of genes from Based on these environmental preferences, a machine-learning algorithm was used to predict the spatial distribution of these dominant families, thereby providing novel insights into important microbial determinants for improved prediction of MeHg production in paddy soils across China.