102. the Production of Amines by Bacteria 2. the Production of Tyramine by Streptococcus Faecalis

IN the first paper of this series, the author [Gale, 1940] showed that washed suspensions of Bact. coli will decarboxylate 1( + )-arginine, 1( + )-lysine, l(+)-ornithine, 1(-)-histidine and l(+)-glutamic acid to form agmatine, cadaverine, putrescine, histamine and y-aminobutyric acid respectively. Of 14 strains of coliform organisms investigated, 12 decarboxylated arginine, 12 histidine, 13 lysine, 12 ornithine and 9 glutamic acid. The decarboxylases involved proved to be very thermolabile and were formed more easily in organisms grown at 27 than in those grown at 37°. The decarboxylase activity of the organisms was shown to depend upon the pH of the medium during growth: organisms grown at pH 7 have little decarboxylase activity but this is greatly increased (20-100-fold) by growing the organisms at pH 5. In most cases the activities were also increased by the presence of glucose in the growth medium but this increase in activity is due to the fall in pH produced during growth by the fermentation acids. The decarboxylases are active over a very restricted pH range, the optimum value in each case being: for arginine, 4 0; lysine, 4-5; histidine, 4 0; ornithine, 5 0 and glutamic acid, 4*0. None of the strains investigated decarboxylated any of the common amino-acids, other than the five mentioned, under the experimental conditions used. Emerson [1902] showed the presence of tyramine in autolysing pancreas, while Rosenheim [1909] and Barger & Walpole [1909] showed it to be one of the main pressor substances in placental extracts and putrefying meat respectively. Sasaki [1914] obtained tyramine from a medium of salts, tyrosine and glycerol heavily inoculated with Bact. coli and incubated, while Hanke & Koessler [1924] obtained this amine by the growth of pure cultures of organisms isolated from the intestine in synthetic media containing tyrosine, salts, glycerol and lactose. As a result of their investigations they suggest that organisms producing histamine are incapable of forming tyramine and vice versa. The present communication deals with the production of tyramine from tyrosine by washed suspensions of Strep. faecalis and describes the properties of the tyrosine decarboxylase present in certain strains of that organism.