The production of amines by bacteria

Abstract

The mixture of washed suspensions of certain Escherichia coli strains with Strep. faecalis has no effect upon the decarboxylation of lysine, histidine, ornithine by the former or of tyrosine by the latter. With arginine, 3 reactions can occur: (1) decarboxylation of arginine to agmatine, (2) breakdown of arginine to ornithine, (3) decarboxylation of ornithine to putrescine. At pH 4 only (1) occurs to any extent; at pH 5.5, all 3 reactions occur, the ratio of the products depending upon the ratio of E. coli/Strep, faecalis present. When these organisms are grown in symbiosis, the activities of E. coli towards lysine, histidine and arginine at pH 4 appear to be the same as those of the pure culture. Towards ornithine, the activity increases 250-300%, probably as a result of the production of ornithine during growth. The organisms grown in symbiosis attack arginine at pH 4 to produce agmatine and at pH 5.5 to give putrescine.