The production of amines by bacteria

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Abstract
Washed suspensions of Strep. faecalis decarboxylate l([long dash])-tyrosine to form tyramine. The decarboxylase involved is optimally active at pH 5. Cultures grown at 27[degree] have the same activity as those grown at 37[degree]. The activity of the washed suspension varies with the age of the culture. The activity also depends upon the pH of the growth medium. Cultures grown in non-carbohydrate media at pH 7 have little activity, this activity being increased 30-40-fold by growth at pH 5. In carbohydrate media the activity obtained is explained by the fall in pH during growth due to fermentation acids. The decarboxylation is quantitative and the tyramine has been isolated and identified as the dibenzoyl derivative. Of 7 strains of Strep. faecalis investigated, 6 decarboxylated tyrosine. These active strains appear to be the more rapid acid-producing strains; 5 strains also formed ornithine by liberation of (NH4)2CO3 from arginine. In no case was any other amino-acid decarboxylated to form an amine under the exptl. conditions descr.

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