Bacterial lecithinases are of special interest because of the possible role of these enzymes in pathogenicity. Lecithinases or phospholipases are enzymes released by bacteria that have the ability to destroy animal tissues. Phospholipid complexes are usually emulsifying agents occurring in tissues, serum and egg yolk. Lecithin is a normal component of the egg yolk. Bacterial lecithinases break down this lecithin to an insoluble diglycerides resulting in an opaque halo, surrounding the colony when grown on the egg yolk agar medium.
In egg yolk agar, the lipoprotein component Lecithovitellin can also be split by lecithinase into phosphorylcholine and an insoluble diglyceride, which results in the formation of a precipitate in the medium. This precipitate occurs as a white halo, surrounding the colony that produces lecithinase enzyme. The opalescence created is due to the release of free fat. Lecithinase activity is used to characterize several gram positive and gram negative bacteria.
Egg Yolk Agar, Modified is a differential and enriched medium used in the isolation and presumptive differentiation of different species based on their lecithinase and lipase production and proteolytic activity. The egg yolk suspension in the medium allows the detection of lecithinase and lipase activity of the microorganism. The degradation of lecithin present in the egg yolk results in the formation of opaque precipitate around the colonies. The Lipase enzyme hydrolyzes the fats within the egg yolk, which results in an iridescent sheen on the colony surface.
Another common reaction observed is proteolysis of the egg yolk as indicated by a clearing of the medium around the colonies. Enzymatic digests of casein and soybean meal supply amino acids and other complex nitrogenous substances. Yeast extract primarily provides the B-complex vitamins. Hemin improves the growth of anaerobic microorganisms. L-cystine is a reducing agent and an essential amino acid.
Bacterial lecithinases are of special interest because of the possible role of these enzymes in pathogenicity. Lecithinases or phospholipases are enzymes released by bacteria that have the ability to destroy animal tissues. Phospholipid complexes are usually emulsifying agents occurring in tissues, serum and egg yolk. Lecithin is a normal component of the egg yolk. Bacterial lecithinases break down this lecithin to an insoluble diglycerides resulting in an opaque halo, surrounding the colony when grown on the egg yolk agar medium.In egg yolk agar, the lipoprotein component Lecithovitellin can also be split by lecithinase into phosphorylcholine and an insoluble diglyceride, which results in the formation of a precipitate in the medium. This precipitate occurs as a white halo, surrounding the colony that produces lecithinase enzyme. The opalescence created is due to the release of free fat. Lecithinase activity is used to characterize several gram positive and gram negative bacteria.Egg Yolk Agar, Modified is a differential and enriched medium used in the isolation and presumptive differentiation of different species based on their lecithinase and lipase production and proteolytic activity. The egg yolk suspension in the medium allows the detection of lecithinase and lipase activity of the microorganism. The degradation of lecithin present in the egg yolk results in the formation of opaque precipitate around the colonies. The Lipase enzyme hydrolyzes the fats within the egg yolk, which results in an iridescent sheen on the colony surface. Another common reaction observed is proteolysis of the egg yolk as indicated by a clearing of the medium around the colonies. Enzymatic digests of casein and soybean meal supply amino acids and other complex nitrogenous substances. Yeast extract primarily provides the B-complex vitamins. Hemin improves the growth of anaerobic microorganisms. L-cystine is a reducing agent and an essential amino acid.
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