Explain Gelatin - Tests for Presence of Exoenzymatic Activity?

Gelatin is an incomplete protein as it lacks amino acid tryptophan. It is a major component of connective tissue and tendons in humans and other animals. Many microorganisms produce an enzyme gelatinase, which result in its hydrolysis. Gelatin deep tubes (Nutrient broth supplemented with 12% gelatin) are used to demonstrate the hydrolytic activity of gelatinase. Gelatin is solid at temperature less than 25°C and liquid at temperature above 25°C. Gelatinase degrades gelatin to produce amino acids and liquefies gelatin. Once this degradation occurs, gel characteristic is not restored even at 4°C. Following inoculation and incubation for 48 hours, if the culture remains liquid, it indicates fast gelatin hydrolysis. If it gets solidified, further incubate for 5 days. If it remain liquefy on refrigeration for 30 minutes, it indicates slow gelatin hydrolysis.