Many attempts have been made for the last six decades to design defined med
ia for species of the lactococcus group. The general outcome of the studies
suggests that this group is heterogeneous with respect Ito specific requir
ements for nutrients. Lactococcal species are limited in various metabolic
pathways. Early attempts to trace the required nutrients were not always su
ccessful because of the poor quality of analysis and the presence of impuri
ties in the medium components.