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Unformatted text preview: 1 Identification of Bacteria: Unknowns Day#3 Physiological Characteristics: Oxidation and Fermentation Tests Materials: (per student ) 1 Glucose broth (10ml) (Ex 5-2) 1 Sucrose broth (10ml) (Ex. 5-2) 1 Lactose broth (10ml) (Ex 5-2) 2 MRVP media (5ml)(Ex 5-4) 1 Mannitol broth (10ml) (Ex 5-2) 1 Nitrate broth (5ml)(Ex 5-7) The MRVP media will be incubated in a separate rack since the VP test requires a 5-day incubation at 37 o C. All other media will be incubated together in the racks provided for 48 hours at 37 o C. Physiological Characteristics: Oxidation and Fermentation Tests Oxidase Test (Ex 5-6) Tests for: presence of cytochrome c or cytochrome a3 which is part of the electron transport chain Reagent: 1% solution of tetramethyl-p-phenylenediamine dihydrochloride positive control Pseudomonas aeruginosa negative control Escherichia coli Students will perform the Oxidase Test on their Unknown bacteria by inoculating a piece of filter paper as indicated in the figure and then adding drops of the Oxidase test reagent. The controls will be available on TSA plates. Results: positive result : dark blue/purple color change within 15 seconds negative result : no color change within 15 seconds P. aeruginosa Unknown E. coli Physiological Characteristics: Oxidation and Fermentation Tests Sugar Fermentation Tubes (with Durham tubes) Tests for: the fermentation of sugars: glucose, lactose, mannitol, and sucrose Reagent :- pH indicator : Phenol Red for detecting acid production upon fermentation; pH of media will drop as acid is produced; (red for pH >7 and yellow for pH <7)- inverted tube (Durham tube): for detecting gas production upon fermentation; if a bubble appears in the tube, then gas was produced Results :- positive : yellow color change for sugar fermentation; bubble in the tube for gas production- negative : red color for no sugar fermentation; no bubble in the tube for no gas production 2 Physiological Characteristics: Oxidation and Fermentation Tests Nitratase Test: Tests for: the presence of nitrate as an electron acceptor in anaerobic respiration and the...
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