Indole formation in Bacterium coli commune

Abstract

O-Amino-[beta]-phenylethanol yields indole in B. coli [Echerichia coli] if O2 is available. The primary step is probably the formation of o-aminophenylacetaldehyde. This reacts spontaneously to form indole. The following hypothesis accounts for the exptl. observations so far available: The biological breakdown of tryptophan begins with an oxidation of C atom 2 of the indole ring leading to an oxindole derivative; this is followed by a ring opening yielding an o-aniline derivative; in the case of indole-forming organisms the side chain of the o-aniline compound is broken down to o-aminophenylacetaldehyde, whence indole arises spontaneously.