Fraser Broth

ReadyTube^® is ready to use media to provide the highest level of quality and testing confidence for improving accuracy and significantly reducing the risk of false results. ReadyTube^® Fraser broth is a selective enrichment medium designed to help the recovery of Listeria sp.

ReadyTube^® Fraser broth is used for the primary and secondary selective enrichment of Listeria sp. from food, animal feed as well as from environmental samples and other materials.

This medium contains peptone, casein, yeast extract, and meat extract, which provide essential nutrients like carbon and nitrogenous compounds, including vitamins, amino acids, and trace ingredients. Phosphates buffer the medium while sodium chloride maintains osmotic equilibrium. Nalidixic acid and acriflavine inhibit the growth of Gram-negative and Gram-positive organisms respectively, except Listeria sp. Listeria sp. hydrolyze esculin to glucose and esculetin. The latter combines with ferric ions of ferric ammonium citrate, resulting in the formation of 6-7-Dihydroxycoumarin, a black-brown complex. Ferric ammonium citrate also enhances the growth of L. monocytogenes. The high salt tolerance (of sodium chloride) of Listeria is used as means to inhibit the growth of Enterococci. Lithium chloride is also used to inhibit Enterococci, which also possess the ability to hydrolyze esculin.

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