1. Ex. 15: Carbohydrate Fermentation
Objectives??

2. Fermentation Tubes Contain
Peptones and NaCl
COH of interest (0.5 – 1%)
Phenol red indicator ( alternate name “phenol red broth or PR broth”)
Use to differentiate Enterobacteriaceae among themselves and from other Gram-neg. rods.

3. Day 1.
Materials needed per table:
Glucose fermentation tubes (3 or 4)
Lactose fermentation tubes (3 or 4)
Sucrose fermentation tubes (3 or 4)
Three pure cultures needed per table:
Enterobacter aerogenes
Pseudomonas aeruginosa
Proteus vulgaris
(E. coli)
Work as a table team. Each student will inoculate one of the organisms into all 3 different fermentation tubes. (If only 3 students per table: Leave out E. coli.)

4. Table 15-1: Possible Results for Carbohydrate Fermentation Tests
Interpretation
Symbol
Yellow broth, bubble in Durham tube
Fermentation with acid and gas as end products
A/G
Yellow broth, no bubble in Durham tube
Fermentation with acid end products; no gas produced
A/
Red or pink broth, no bubble in Durham tube
No fermentation; more or less degradation of peptones with varying quantities of alkaline end products
/
K if pH

5. Possible Reactions

6. Day 2.
Glucose Fermentation with Durham Tube

7. Lactose Fermentation

8. Sucrose Fermentation

9. Results for Fermentation Broth Tubes
Organism
Carbohydrate
Glucose
Lactose
Sucrose
Growth
Acid
Gas
Read as
E. aerogenes
P. aeruginosa
P. vulgaris
The End