Tyrosine Decarboxylation by Streptococci: Growth Requirements for Active Cell Production

The present work was undertaken because of a need for more information-concerning the factors favoring tyrosine decarboxylation. A tyrosine decar-boxylation system in Streptococcus fecalis was described by Gale (1940). Since the conditions for active dehydrogenase formation have previously been shown to differ from those which favor the largest cell crop, optimum function was sought and abundant growth was considered only as a secondary aim. In the production of active cells the growth conditions and the specific nutritive require-ments will depend to a large extent on the enzyme system under consideration. For example, Wood and Gunsalus (1942) found the most active dehydro-genases in streptococcus cells harvested from media rich in nitrogen and acces-sory factors and low in carbohydrate. With a limited amount of carbohydrate the final pH was near neutrality and, since growth was limited, a high concentra-tion of nutrilites was available per cell when growth ceased. The optimum age of culture was just beyond the logarithmic growth phase. In contrast to this, Gale (1940) had found that Streptococcus fecalis cells possess the most active