Lee's agar is used for differential enumerations of yoghurt starter bacteria ( Lactobacillus bulgaricus and Streptococcus thermophilus ).This medium described by Lee et al is used for the differential enumeration of yoghurt starter bacteria. This medium is also recommended by APHA for the same purpose. It contains sucrose, which most L. bulgaricus strains will not ferment, but S. thermophilus will, and lactose, which both species utilize. Bromocresol purple is the pH indicator, which turns yellow in acidic condition and imparts yellow color to the colony. Lactobacillus bulgaricus shows luxuriant growth on media with white colored colony; while Streptococcus thermophilus grows luxuriantlly giving yellow colored colony.
Application: For Laboratory Chemicals, Analytical Purpose, Biochemical Analysis
- Appearance: Light yellow to light grey homogeneous free flowing powder
- Gelling: Firm, comparable with 1.8% Agar gel
- Color and Clarity of prepared medium: Purple colored, opaque gel forms in Petri plates
- Reaction: Reaction of 5.15% w/v aqueous solution at 25°C. pH : 7.0±0.2
- Cultural Response: Cultural characteristics observed in presence of Carbon dioxide (CO2),after an incubation at 35-37°C for 48 hours