ID#: 21007
Description: Caption:
This image depicted six test tubes, each containing a growth medium of egg yolk, and each having been inoculated with a different strain of Listeria monocytogenes, which produced the classic egg yolk reaction (Eigelb-Reaktion). The opacification of the egg yolk medium is a direct indication as to the ability of the strain of L. monocytogenes to produce the enzyme lecithinase, a phospholipase-type enzyme, which is used as an indicator as to the organism’s pathogenicity. Note the opacification, or positive reaction, in the tubes marked, “positiv”. As you can see here, not all strains of L. monocytogenes possess the ability to produce lecithinase, as indicated by the negative sample labeled, “negativ”, situated to the left of the uninoculated tube labeled, “unbeimpft”. Due to their ability to emulsify, phospholipase-type enzymes have the ability to destroy animal tissues.
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Content Providers(s): CDC/ Charles N. Farmer
Creation Date: 1965
Photo Credit: Dr. Heinz Seeliger
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Copyright Restrictions: Yes - This image is copyright protected. Any public or private use of this image is subject to prevailing copyright laws. Please contact the content provider of this image for permission requests.