Lactobacillus Bulgaricus Agar Base with acetate buffer is recommended for isolation and identification of Lactobacillus bulgaricus. This medium was originally formulated by Kulp and White for the recovery of Lactobacilli. Further modification is recommended by APHA for isolation and identification of L. bulgaricus from foods. Streptococcus thermophilus and L. bulgaricus are the essential microbial species and are active in symbiotic relationship in yoghurt. Because of the emphasis on maintaining a balance between cocci and rods, techniques are needed to determine the relative proportions of S. thermophilus and L. bulgaricus when grown together in milk cultures.