OF Medium w/ Dextrose is supplied by HiMedia. It is a sterile ready prepared media containing 5ml of green coloured solution in bottles. OF Medium w/ Dextrose is generally used for differentiation of gram-negative bacteria on the basis of fermentative and oxidative metabolism of dextrose. It is advisable to store this ready prepared media between 2-8C. Composition (in gm/L) is as follows:

Casein enzymic hydrolysate (2.00)

Sodium chloride (5.00)

Dipotassium phosphate (0.30)

Bromo thymol blue (0.08)

Dextrose (10.00)

Hugh and Leifson developed OF Medium to study oxidative and fermentative metabolism of carbohydrates by gram negative bacteria. This criterion is used during taxonomic studies of Enterobacteriaceae. Casein enzymic hydrolysate in the medium provides the necessary carbon and nitrogen, vitamins etc required for bacterial growth. A carbohydrate whose fermentation reaction is to be studied is added separately. Phosphate buffers the medium and the low agar concentration determines motility and dispersion of the acid produced on the surface. Bromothymol blue acts as the pH indicator. Low concentration of agar in the medium permits the determination of motility and aids in the even distribution of any acid produced at the surface of the medium. Motility is observed as diffused zone of flaring out from the line of inoculation. Non-motile organisms grow along the line of inoculation. Dextrose is the most important carbohydrate used in OF Basal Medium. However, certain organisms may metabolize other carbohydrates even if they are unable to utilize dextrose.