- Slides: 9
Bacterial enzymes Lab. 7 A. L. Noor Ameer
Biochemical tests use for establishing enzymatic capabilities • 1 - Catalase test: • Aim: used to determine the ability of bacteria to produce catalase enzyme which catalyzes the decomposition of hydrogen peroxide to water and oxygen
• 2 - Oxidase test: • Aim: used to determine the ability of bacteria to produce indophenol oxidase which catalyze the transport of electrons from donor compounds (NADH) to electron acceptors (usually oxygen). • 3 - Urease test: • Aim: used to determine the ability of bacteria to produce the urease enzyme which hydrolyzes urea that found in urea broth to ammonia & water.
• 4 - Gelatinase test: • Aim: used to determine the ability of bacteria to produce an exoenzyme, called gelatinase that hydrolyzes gelatin. • 5 - Starch hydrolysis test: • Aim: used to determine the ability of bacteria to produce α-amylase that hydrolyzes starch to maltose.
• 6 - IMVIC tests: • a- Indole Production Test : Aim: used to determine the ability of bacteria produce Tryptophanase enzyme which degrade the tryptophan to indole, pyruvic acid & ammonia. • b- Methyl Red Test (MR test) : • Aim: - used to determine the ability of microbes to oxidize glucose with production of high content of acid end product.
• c- Voges – Proskauer Test (Vp Test) : • Aim: used to detect acetoin or Acetyl Methyl Carbinol production in a bacterial broth culture. • d- Citrate Utilization Test : • Aim: used to determine the ability of the microbes to ferment citrate as sole carbon source. -
• 7 - Nitrate reduction: • Aim: used to determine the ability of bacteria to reduce nitrate (NO 3) to nitrite (NO 2) & then to molecular nitrogen (N 2) by using of nitrate broth. • 8 - Triple Sugar Iron Agar (TSI) (Kligler's iron agar): • Is a differential medium that contains lactose, sucrose, a small amount of glucose (dextrose), ferrous sulfate, and the p. H indicator phenol red. It is used to differentiate enterics based on the ability to reduce sulfur and ferment carbohydrates.
The Analytical Profile Index or (API) system • is a classification of bacteria based on experiments, allowing quick identification of clinically bacteria. • Some of their types: • 1 - API 20 E/NE: identification system combines some conventional tests and allows the identification of a limited number of Gramnegative Enterobacteriaceae or non-Enterobacteriaceae
• 2 - API-Staph: is specific for Gram positive bacteria, including Staphylococcus species, Micrococcus, species, and related organisms • 3 - API- 20 Strep: for streptococci and enterococci • 4 - API- Coryne: for Corynebacteria