ABSTRACT

The attachment of a methyl group to a metal(loid) atom by a living organism - the process of biomethylation - can profoundly influence the chemical, physical, and toxicological properties of the element. Although microbial biomethylation of inorganic antimony (Sb) has been suspected for the past half-century, the first characterisation of a volatile antimony compound (trimethylstibine) thought to arise biogenically from inorganic antimony was not until 1996. Since that time, antimony biomethylation has been demonstrated for various microbial enrichment cultures and, in pure culture, for certain eubacteria, archaea, yeasts, filamentous fungi and yeasts. Scopulariopsis brevicaulis has been a focus of research into antimony biomethylation, particularly in relation to the toxic gas hypothesis for sudden infant death syndrome (SIDS). This review synthesises current knowledge on microbial biomethylation of inorganic antimony compounds in regards to organisms and culture conditions, biotransformation products and biological mechanisms. The related topics of (l) occurrence of methylantimony compounds in the aquatic environment and in biota, (2) hydride generation for analysis for organoantimony compounds, (3) reactions that relate to the environmental mobility of methylantimony compounds, (4) toxicology of antimony compounds and (5) antimony biomethylation in the context of SIDS research, are also considered.