MRS BROTH w/o DEXTROSE and w/o BEEF EXTRACT 500 grams/bottle

MRS Broth w/o Dextrose and w/o Beef Extract has the same formulation as MRS Broth (Cat. 1215) but without beef extract and dextrose. The medium is used when a carbohydrate different to glucose has to be tested. Ammonium citrate at a low pH inhibits most microorganisms, but allows the growth of lactobacilli. Dipotassium phosphate and sodium acetate are buffer agents to maintain a low pH. Tween 80 is an emulsifier; Manganese and magnesium sulfates are sources of ions and sulfate. Casein peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is source of vitamins, particularly the B-group. MRS Broth may be used for other tests in the identification of of lactobacilli such as temperature dependence, growth in 4% NaCl, growth in 0,4% Teepol, etc. as recommended by Sharpe, Fryer and Smith. The growth of some Lactobacillus strains are inhibited at a higher pH of 6,0 and it is necessary to acidify the media to promote the growth. To acidify the media some drops of acetic acid can be added.