To differentiate gram negative rods, particularly E.coli

Litmus milk decolorization test

To differentiate S. pneumoniae from other alpha-hemolytic streptococci (viridans streptococci)

Catalase test: Used to differentiate those bacteria that produce the enzyme catalase, such as streptococci , from non-catalase producing bacteria such as staphylococci .

Catalase act as a catalyst in the breakdown of hydrogen peroxide to oxygen and water

Citrate utilization test used occasionally to assist in the identification of enterobacteria

If the bacteria utilize the citrate it will liberate CO2 which combine with sodium and result in sodium carbonate which is an alkaline product that change the color of the indicator from blue to green which is considered a positive reaction.

Coagulase test is used to identify _______ which produces the enzyme coagulase.

Free coagulase : converts fibrinogen directly to fibrin without requiring a coagulase reacting factor

Indole production is detected by ______ reagent which contains 4 (p)-dimethylamino-benzaldehyde

In oxidase test , reagent will be oxidized to

Urease test , one of the following is false

This test detect the formation of a neutral
product (acetyl methyl carbinol) during fermentation of glucose. This can be detected by the addition of Barritt's reagent after incubation. The development of a red color is considered a positive result.

TSI test : This reaction is for lactose fermenting bacteria, which ferment the lactose that present in large amounts in the medium(1 %)

TSI test
Bubbles or break in the medium : due to the formation of gas.

All the following are characteristics of Enterobacteriaceae except

The green metallic sheen indicates _______ is able to ferment lactose to produce strong acid end-products.