M17 Broth is a selective medium generally used for cultivation, enumeration and enrichment of lactic acid bacterium Lactococcus lactis. It is also used for the enrichment of Streptococcus thermophilus bacteria. M17 Broth includes the buffering agent Disodium-β-glycerophosphate, which helps maintain a stable pH by neutralizing organic acids, like lactic acid, produced during the fermentation process.