Effects of Glucose on the Production by Escherichia coli of Hydrogen Sulphide from Cysteine

SUMMARY: Glucose and certain other sugars accelerated hydrogen sulphide production from l-cysteine by washed cells of Escherichia coli (strain Crookes) which had been grown in the presence of l-cysteine. On the other hand, glucose or some other sugars in protein hydrolysate media containing l-cysteine suppressed the synthesis of an enzyme(s) which mediates the formation of hydrogen sulphide from l-cysteine. Glucose accelerated sulphide formation from l-cysteine by sonicated preinduced cells, although activity was unstable to such treatment. Both effects of glucose were influenced by the amino acid content of the medium. Sulphide production probably resulted through the action of cysteine desulphydrase; certain evidence suggested that a transaminase linked to β-mercaptopyruvate desulphurase also may have functioned. Apparently glucose repressed the induction of one or more enzymes concerned with cysteine degradation.