The production of indole by suspensions of <i>Bact. coli</i>

Abstract

WOODS [1935, 1] has studied the conversion of tryptophan into indole by washed suspensions of Bact. coli. He found that the process was an oxidation requiring 5 atoms 0 per mol. tryptophan. The conversion of tryptophan to indole was complete and the rate of disappearance of tryptophan was the same as the rate of formation of indole. The coil suspensions used by Woods were prepared from growths on trypsin-digested casein solidified with agar, and thus had always been produced in the presence of tryptophan. Happold & Hoyle [1935] also studied the oxidation of tryptophan and found on two out of three occasions that slight activity was present in suspensions grown in the supposed absence of tryptophan on Fraenkel's synthetic medium. Since this medium, however, contained natural asparagine [Dr Happold, private communication] it is possible that tryptophan might have been present as an impurity in biologically significant amounts. It was therefore decided to test the production of the enzyme under conditions in which tryptophan was certainly absent.