Fraser Broth Supplement (Fraser Broth)
Fraser Broth Supplement is used with Fraser Broth Basein selectively enriching and detecting Listeria.
Principles Peptones, beef extract and yeast extract provide nitrogen, vitamins and minerals. Sodium phosphate and potassium phosphate are buffering agents. Differentiation is aided by including ferric ammonium citrate in the final medium. Since all Listeria species hydrolyze esculin, the addition of ferric ions to the medium will detect the reaction. A blackening of the medium by cultures containing esculin-hydrolyzing bacteria is the result of the formation of 6,7-dihydroxycoumarin that reacts with the ferric ions.7 Selectivity is provided by the presence of lithium chloride, nalidixic acid and acriflavine in the formula. The high salt tolerance of Listeria is used as a means to inhibit growth of enterococci.
Note This product is required for use with the Fraser Broth Base. This product can be found at the link below.