Mercury compounds accumulate in the Mariana Trench through sinking particles or carrion, yet the mercury cycling process and how hadal trench microbes cope with mercury toxicity remain largely unexplored. In this study, we investigated the biogeochemistry of mercury in Mariana Trench sediments using metagenomic (n = 58) and metatranscriptomic (n = 10) analyses. Our results revealed a widespread presence of genes involved in methylmercury demethylation ( merB ) and Hg²⁺ reduction ( merA ), as well as sulfate reduction and sulfur oxidation, all contributing to mercury detoxification. Further analysis identified significant differences in transcriptomic activity between slope and bottom sediments, suggesting distinct mercury fates in these environments. These findings emphasize the role of the sulfur cycle in shaping Hg detoxification in hadal trenches, inspiring the understanding of the mercury cycle in the deepest point of the ocean.
Lv et al. (Wed,) studied this question.