[³⁵S]Cyclamate Metabolism: Incorporation of ³⁵S into Proteins of Intestinal Bacteria in vitro and Production of Volatile ³⁵S-Containing Compounds

Abstract

1. A washed whole-cell suspension of bacteria prepared from the faeces of rats regularly fed oral cyclamate incorporated ³⁵S into bacterial protein when challenged with [³⁵S]cyclamate. Control preparations showed low-level incorporation of label.

2. Radioactivity was also accounted for as volatile ³⁵S-containing compound(s), soluble in sodium hydroxide.

3. Addition of cysteine to incubation mixtures inhibited incorporation of ³⁵S into proteins.

4. The results suggest that the bacterial conversion of cyclamate to the suspected bladder carcinogen, cyclohexylamine, is controlled by the prevailing sulphur metabolism of the intestinal bacteria.