The formation of indigotin from indol by soil bacteria

Abstract

Indol (C 6 H 4 CH : CH . NH) has a wide distribution in nature, being present an several plants and also produced by putrefactive changes in the intestine. There is no evidence as to its fate after decomposition in soil or in sewage. Its non-persistence at the moderately high temperatures of the manure heap may be due to its volatility; its disappearance from sewage and manured soil may have to be assigned to some other cause. Supniewski states that Bacillus pyocyaneus can decompose indol with the production of antkranilic ( o -aminobenzoic) acid, although the action is extremely slow. In attempting to isolate from soil by the usual selective method of cultivation bacteria capable of destroying indol, it was found that in mineral salt solution containing indol, the latter rapidly disappeared, some colourless compounds being formed whose nature has not been determined. Two organisms have, however, been isolated that can decompose indol with the formation of blue crystals. The chief cultural characters of these two organisms are described below.