Streptococcus lactis Differential Agar Base is recommended for differentiation of citrate utilizing lactic Streptococci-Lactococcus lactis (Streptococcus lactis) subspecies diacetylactis from citrate nonutilizing Lactococcus lactis (Streptococcus lactis) and Lactococcus lactis (Streptococcus lactis) subspecies cremoris. This medium is formulated as described by Kempler and McKay.