Tryptone Glucose Yeast Extract Agar was originally developed by Bowers and Hucker (1) which they called as Tryptone Glucose Skim Milk Agar. Later on it was modified to the present composition for the cultivation and enumeration of bacteria in air, water (2), milk and dairy products (3). Various authors have studied different aspects of this medium like study of thermophilic bacteria in milk (4), influence of incubation temperature (5) etc. It is used as a standard medium for the bacteriological plate count of milk and dairy products (6).
Casein enzymic hydrolysate, yeast extract provide nitrogenous compounds, vitamin B complex and other essential growth nutrients. Glucose is the energy source. For the enumeration purposes, pour plate method is suggested. Medium must be quickly poured into Petri dishes if milk sample is to be tested, because the milk may get flocculated if the medium remains hot for longer period of time.
Storage and Shelf-life:
Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label.
References:
1. Bowers and Hucker, 1935, Tech. Bull., 228, N.Y.State Agr. Expt. Station.
2. Eaton A. D., Clesceri L. S. and Greenberg A. W., (Eds.), 2005, Standard Methods for the Examination of Water and Wastewater, 21st Ed., APHA, Washington, D.C.
3. Wehr H. M. and Frank J. H., 2004, Standard Methods for the Microbiological Examination of Dairy Products, 17th Ed.,APHA Inc., Washington, D.C.
4. Pickett, 1928, Tech. Bull. 147, N.Y. State Agr. Expt. Station.
5. Dennis and Weiser, 1937, J.Dairy Science, 20 : 445.
6. Abele C. A., Am. J. Pub. Health, 1939, 29: 821.