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 ResultInterpretationSymbol 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