Hydrolysis Tests Flashcards
Why is casein hydrolysis necessary for cells
Casein is a large protein, so bacteria secrete exoenzymes to catalyze the hydrolysis of proteins into peptides or amino acids, which makes nutrients available for cellular uptake for use in bacterial synthesis or as an energy source
What is tributyrin
The simplist triglyceride in natural oils and fats, found in butter and margarine
- triglycerides of 3 fatty acid chains and glycerol, hydrolysis is necessary for cellular uptake
What does the starch hydrolysis test identify
Organisms that contain enzymes alpha-amylase and oligo-1,6-glucosidase which break the linear and branched glycosidic linkages and hydrolyze starch into smaller polysaccharides and glucose to be absorbed
What is starch composed of
Glucose subunits in linear (amylose) and branched (amylopectin) forms
Why is iodine added after incubation? (Starch hydrolysis)
Starch and sugar subunits are soluble and difficult to see so iodine is added after incubation
What does the gelatin hydrolysis test identify
Determines a microbe’s ability to produce gelatinase exoenzymes, a family of exoenzymes that hydrolyze gelatin into amino acids that can be absorbed by the cell
What is gelatin
Protein derived from collagen and is a key part of connective tissue vertebrae
What does the urease test detect
Determines an organism’s ability to hydrolyze urea.
- urea results from decarboxylation of amino acids, it can turn into ammonia and carbon dioxide by bacteria with urease
How are rapid urease-positive organisms indicated
Rapid urease-positive organisms overcome the potassium phosphate buffer, alkalinizing the medium and turning the broth pink
How are slow urease positive and urease-negative cells indicated
These organisms don’t overcome the potassium phosphate buffer and hydrolyze urea, so the pH stays constant resulting in orange or yellow broth
