Biosynthesis of Methylmercury Compounds by the Intestinal Flora of the Rat

Abstract

The contents of the rat cecum and, to a lesser extent, those o f the small intestine, synthesized methylmercury from mercuric chloride labeled with Hg 203 in vitro under aerobic or anaerobic conditions. The rate o f formation was approximately 18 ng/g cecal contents/20 hr, The synthesis o f methylmercury was inhibited by antibiotics and by filtration of the cecal contents through membrane filters, indicating that the bacterial flora of the gut participates in the reaction. Pure cultures of bacteria, isolated from the intestinal tract of the rat, could methylate mercuric chloride. It was estimated that the total amount of methylmercury synthesized from ingested inorganic mercury in man is approximately 400 ng/day.