Part 2 book “Practical manual of medical microbiology” has contents: Bile solubility test, antimicrobial susceptibility testing, brucella agglutination test, treponema pallidum haemagglutination assay, enzyme linked immunosorbent assay, experimental animals, fungal slide culture, medical entomology, and other contents. | 28 Nitrate Reduction Test ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ PRINCIPLE This test detects the presence of enzyme nitrate reductase which causes the reduction of nitrate to nitrite in the presence of a suitable electron donor. Almost all Enterobacteriaceae members reduce nitrate. Nitrate reduction can be detected by an appropriate colorimetric reagent. Requirement 1. Medium Potassium nitrate - gm Peptone - 5 gm Distilled water - 1litre Tube in 5 ml amounts and autoclave at 121oC for 15 min. 2. Test reagent Solution A - Dissolve 8 gm sulphanilic acid in 1 litre of acetic acid 5 mol/lit Solution B - Dissolve gm of α-naphthylamine in litre of acetic acid 5 mol /litre immediately before use, mix equal volume of solution A and B to give the test reagent. Nitrate Reduction Test 119 Method • Inoculate the medium with test organism • Incubate at 37 oC for 96 hours. • Add ml of the test reagent to the test culture. Result A red color within a few minutes - Nitrate reduction positive color - Nitrate reduction negative . Acinetobacter. 29 Hydrogen Sulphide Production Test ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ PRINCIPLE Some gram negative bacillii produce H2S by breaking down sulphur containing amino acids like cysteine or cystine. Hydrogen sulphide is demonstrated by its ability to form black insoluble sulphides. Method 1 There are different methods and media are used for detection H2S production. List of media used for H2S detection 1. 2. 3. 4. 5. 6. Bismuth sulfite agar. Triple sugar iron agar (TSI). Lysine iron agar. Lead acetate agar. Kigler iron agar. Deoxycholate citrate agar. Hydrogen Sulphide Production Test 121 Method 2 Filter paper method. • Prepare a Whatman filter paper impregnated with lead acetate (10% solution) • Expose the filter paper above culture by placing filter paper between the cotton plug and test tube. Result Blackening of the .
