Bacterial Degradation via Indole. The Tryptophanase Reaction

The adaptive formation of tryptophanase has been studied by Happold and his colleagues (202, 339, 340). 

Some bacteria can further degrade indole. This reaction has been studied by Uchida and colleagues. Experiments using successive adaptation (742) suggested the following pathway  

4- Origin of Urinary Indican, Indigo, Indiruhin, Skatoxyl, and Skatole Red 

Urinary indican is the 0-sulfate of indoxyl (usually isolated as the potassium salt, 414) and is excreted by mammals as a detoxication product of the 

Indican was early considered to be a normal constituent of human urine (413), but this was disputed by later workers, probably owing to the inadequate sensitivity of the tests employed. Its normal occurrence is now established (87, 175). Indole produces nausea, headache, and other unpleasant symptoms (649), whereas indican is pharmacologically almost inactive (435). Indican formation is therefore a true detoxication, but in man only about 30% to 50% of ingested indole is converted to indican (87, 649). A good deal of the indole produced in the gut appears in the feces, indole and the related skatole (3-methylindole) being largely responsible for the typical fecal smell. 

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