Gelatin Hydrolysis
Some microorganisms possess an enzyme called gelatinase, which breaks down gelatin into amino acids. Gelatin deeps contain the substrate gelatin, which is a protein produced by the hydrolysis of collagen. Organisms which hydrolyze gelatin will cause the gelatin to liquefy.
Tube #1 is negative for gelatin hydrolysis.
Tube #2 is positive for gelatin hydrolysis.