Purpose: To differentiate between organisms that produce the exoenzyme gelatinase and those that do not.
Principle: Gelatin is a protein that is derived from collagen. The gelatin molecule is to large to enter the cell as a whole so the exoenzyme gelatinase cleaves gelatin to polypeptides and then further degrades polypeptides to amino acids which are taken up and utilized by the cell. When gelatin is converted to these smaller subunits it takes on a liquid form, this is the basis for this test
The tubes to the right depict a gelatinase negative (A) and gelatinase positive (B and C) reactions.