M17 AGAR WITH GLYCEROPHOSPHATE

Description

M17 media are based on the formulation described by Terzaghi and Sandine for the cultivation and enumeration of lactic Streptococci and their bacteriophages. It is possible to study plaque morphology and lysogeny. M17 Agar is recommended by the International Dairy Federation for selective enumeration of Streptococcus thermophilus from yoghurt. M17 Agar is recommended by APHA for the cultivation of lactic Streptococci. Shankar and Davies reported isolation and enumeration of Streptococcus thermophilus from yoghurt. It is also suitable for cultivation and maintenance of starter cultures for cheese and yoghurt manufacturing. This medium helps in detecting streptococcal mutants that are lactose non-fermenters. Lactic nStreptococci are nutritionally fastidious and require complex media for optimal growth. Disodium glycerophosphate maintains the pH above 5. The maintenance of pH is very important as lower pH results in injury and reduced recovery of lactic Streptococci. Glycerophosphate does not form precipitate with calcium which is needed for the plaque assay of lactic bacteriophages.