click below
click below
Normal Size Small Size show me how
Enterobacteriaceae 2
Types of Testing: Amino Acid Utilization
Test Name | Principle of Test | Process |
---|---|---|
Dehydrolization | remove hydrogen | Arginine - two step process = convert Ornithine then decarboxylated to give reaction |
Deamination | remove the amine (NH2) group | Phenylalanine (occurs in the presence of oxygen) = reaction is demonstrated by addition of 10% ferric chloride to produce a green color |
Lysine Iron Agar - LIA | contains glucose, peptones, 2 pH indicators / provide a favorable environment for decarboxylation to take place = acid & anaerobic | oil added after inocculation / purple color = positive reaction / black color = H2S production / All purple (K/K) = positive / Top purple/butt yellow (K/A) = negative / K/A (Top purple/butt black) = H2S positive / N/A (Top pink/butt yellow) = negative |
Decarboxylase | converts amino acids to amines - cleaves the carboxyl group from amino acid | Lysine (amino acid) - Lysine decarboxylase - Cadaverine (amine) + CO2 Ornithine (amino acid) - Ornithine decarboxlyse - Putrescine (amine) + CO2 |