Monomethylmercury degradation by the human gut microbiota is stimulated by protein amendments

Area of Science:

• Environmental Science
• Microbiology
• Toxicology

Background:

• Monomethylmercury (MMHg) is a potent neurotoxicant biomagnified in food chains.
• Human exposure to MMHg poses significant health risks.
• The gut microbiota's role in MMHg absorption and body burden variation is recognized but poorly understood.

Purpose of the Study:

• To investigate the impact of dietary nutrient changes on mercury (Hg) metabolism within the human gut microbiota.
• To elucidate the relationship between gut microbial function and MMHg transformation.

Main Methods:

• In vitro experiments using anoxic fecal slurry incubations.
• Stable Hg isotope tracers to track MMHg production and degradation.
• High-throughput sequencing of the 16S rRNA gene to characterize microbial communities.

Main Results:

• MMHg degradation is highly individual-dependent.
• Microbial MMHg degradation rapidly responds to dietary nutrient amendments.
• Complete degradation of MMHg was observed under specific nutrient conditions.
• The degradation mechanism does not appear to involve the known mer operon.

Conclusions:

• This study demonstrates, for the first time, a nutrient-dependent ability of simulated human gut microbiota to demethylate MMHg.
• Findings highlight the influence of diet on gut microbial Hg metabolism.
• Provides crucial insights into individual variations in mercury absorption and toxicity.