M17 Agar w/ Glycerophosphate is used for the cultivation of lactic Streptococci and plaque assay of lactic bacteriophages. It is recommeded by APHA for the cultivation and enumeration of lactic Streptococci and their bacteriophages. It is possible to study plaque morphology and lysogeny, also recommended by the International Dairy Federation for selective enumeration of Streptococcus thermophilus from yoghurt