M17 agar
This bacterial growth medium was developed in 1971 for Lactococcus species isolated from milk products. It was originally called M16 medium,[1] but in 1975 Terzaghi and Sandine[2] added disodium-β-glycerophosphate to the medium as a buffer, and named the new growth medium M17 medium. It was later found that the addition of disodium-β-glycerophosphate inhibits the growth of many Lactobacillus species.[3]
Typical composition
Per 950 mL:[2]
- 5.0 g Pancreatic digest of casein
- 5.0 g Soy Peptone
- 5.0 g Beef extract
- 2.5 g Yeast extract
- 0.5 g Ascorbic acid
- 0.25 g Magnesium sulfate
- 19.0 g Disodium-β-glycerophosphate
- 11.0 g Agar
Preparation:
- 1. Heat with frequent agitation and boil for 1 minute to completely dissolve.
- 2. Autoclave at 121 °C for 15 minutes. Cool to 50 °C.
- 3. Add 50 ml filter sterilized 10% lactose solution and mix well (the lactose can be exchanged to other carbohydrates e.g. glucose, resulting in GM17 medium)
References
- ^ Lowrie RJ, Pearce LE (1971). "The plating efficiency of bacteriophages of lactic streptococci". N.Z. J. Dairy Sci. Technol. 6: 166–171.
- ^ a b Terzaghi BE, Sandine WE (1975). "Improved medium for lactic streptococci and their bacteriophages". Applied Microbiology. 29 (6): 807–813. doi:10.1128/am.29.6.807-813.1975. PMC 187084. PMID 16350018.
- ^ Shankar PA, Davies FL (1977). "A note on the suppression of Lactobacillus bulgaricus in media containing β-glycerophosphate and application of the media to selective isolation of Streptococcus thermophilus from yoghurt". International Journal of Dairy Technology. 30 (1): 28–30. doi:10.1111/j.1471-0307.1977.tb01162.x.