Tyrosine Decarboxylation by Streptococci: Growth Requirements for Active Cell Production

Abstract

With Streptococcus jaecalis, the nutritional requirements for the production of cells with max. tyrosine decarboxylase activity are more specific than those for max. growth. In accord with the data of Gale, acid growth conditions were found to favor tyrosine decarboxylation. This contrasts with the finding that neutral growth conditions favor the production of some dehydrogenases. The activity of the cells was tested in phthalate buffer at pH 5 with the conventional Warburg methods. Using a glucose tryptone yeast-extract medium the activity of the cells was found to vary inversely with the quantity of growth, indicating that one of the factors essential for the system was present in limited amt. When the medium was simplified, acid-hydro-lyzed gelatin plus tyrosine, trypto-phane, and cystine replaced the tryptone. More tyrosine was required for decarboxylase production than for max. growth. When the yeast extract of the medium was replaced by vitamins, purines, and a mineral mixture, pyridoxine and nicotinic acid were required in greater conc. for max. tyrosine decarboxylation than for growth. This may indicate a function of these vitamins, or their derivatives, in the decarboxylation system.