Biochemical Model for the Biological Methylation of Mercury suggested from Methylation Studies in vivo with Neurospora crassa

SINCE the discovery of methyl mercury formation in lake sediments contaminated with inorganic or phenyl mercury 1 , there has been a good deal of speculation about the mechanism of this synthesis. One process involving methyl-cobalamin (a B 12 -derivative) was demonstrated in cell-free extracts of methanogenic bacteria 2 . Vitamin B 12 is not known to be involved in the metabolism of Neurospora 3,4 , and so we have investigated the biosynthesis of methyl mercury in this organism, where the pathway should be different.