Ex. 16: Carbohydrate Fermentation

Objectives??

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.

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.)

Day 1.

Table 16-1: Possible Results for Carbohydrate Fermentation Tests

Result Interpretation SymbolYellow 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

Possible Reactions

Glucose Fermentation with Durham Tube

Lactose Fermentation

Sucrose Fermentation

Results for Fermentation Broth Tubes

Organism

Carbohydrate

Glucose Lactose Sucrose

Growth Acid Gas Read as Growth Acid Read as Growth Acid Read as

E. aerogenes

P. aeruginosa

P. vulgaris

The End