1. Exercise 39: Oxidation and Fermentation Tests
Lab 9 Goals and Objectives:
Read results
Exercise 39: Oxidation and Fermentation Tests
some tubes will require additional reagents
Share and record all class results
Exercise 38: Cultural characteristics
Each person inoculate one nutrient Gelatin deep
Exercise 40: Hydrolytic and Degradative Reactions
Each person inoculate one Urea broth
Exercise 41: Multiple Test Media
Each person inoculate one SIM media deep
Exercise 69: Gram Negative Intestinal Pathogens
Each person inoculate one MacConkey agar plate
Make new streak for isolation on BHIA

2. Durham Sugar Tube Fermentation (Lactose or Mannitol)
Contains: single carbohydrate peptone broth with durham tube for gas collection, Phenol red pH indicator: alkaline pH = red, acidic pH = yellow
Discriminates the ability to ferment a single carbohydrate (glucose, lactose, or mannitol) into acid products (e.g. pyruvic acid) or acid plus gas
Results: Red = inert, negative for fermentation of specified
carbohydrate
Yellow = positive for fermentation of carbohydrate to acid products
Yellow with bubble = positive for fermentation of carbohydrate to acid + gas

3. Acid plus gas
Acid
Negative

4. _ + MR-VP Medium: Methyl Red Test
Contains: peptone, glucose, and buffer (buffer will neutralize weak acids so only strong stable acids will be detected by methyl red)
Additional reagents added: methyl red pH indicator: acid pH = red, neutral or alkaline pH = yellow
Distinguishes ability to catabolize glucose into stable mixed acids (lactic, acetic, and formic acids) in the mixed acid pathway
Results: Red = positive for mixed acid formation
Yellow = negative for mixed acid formation _ +

5. _ _ + + MR-VP Medium: Voges-Proskauer Test
Contains: peptone and glucose
Additional reagents added: Barritt’s A (alpha napthol) and Barritt’s B (KOH) (will react with acetoin to produce a red product, alone produce a copper colored product)
Distinguishes the ability to catabolize glucose into the neutral end product butanediol (the oxidized product is acetoin) in the butylene glycol pathway
Results: Red = positive for acetoin and thus for 2,3-butanediol
production
Yellow/Orange = no acetoin, negative for 2,3-butanediol production _ _ + +
Control
Enterobacter cloacae

6. _ + Simmon’s Citrate Agar
Contains: citrate as sole carbon source, ammonium salts as sole
nitrogen source, bromthymol blue pH indicator: neutral pH = green, alkaline = prussian blue
Discriminates organisms that can produce citrase to metabolize citrate into oxaloacetate and pyruvate. These organisms are forced to utilize ammonium salts as the nitrogen source producing alkaline ammonia waste.
Results: Prussian blue slant and or butt = positive for
citrase production
Green = negative for citrase production _ +
CitrateOxaloacetate 
Pyruvate + ammonium salt
Fermentation Alkaline pH
Control: Enterobacter cloacae

7. New inoculation from single colonies on BHIA:
Nutrient gelatin deep – stab with needle
(Exercise 38)
Urea broth – loop
(Exercise 40)
SIM media deep – stab with needle
(Exercise 41)
MacConkey agar plate – loom streak for isolation
(Exercise 69)
Make new streak for isolation on BHIA
Discard old plates and tubes

8. Exercise 39: Oxidation and Fermentation Tests
Lab 9 Goals and Objectives:
Read results
Exercise 39: Oxidation and Fermentation Tests
some tubes will require additional reagents
Share and record all class results
Exercise 38: Cultural characteristics
Each person inoculate one nutrient Gelatin deep
Exercise 40: Hydrolytic and Degradative Reactions
Each person inoculate one Urea broth
Exercise 41: Multiple Test Media
Each person inoculate one SIM media deep
Exercise 69: Gram Negative Intestinal Pathogens
Each person inoculate one MacConkey agar plate
Make new streak for isolation on BHIA