Miscellaneous Reactions

Catalase Test

• Detects the presence of catalase, an enzyme that breaks down hydrogen peroxide (H2O2) into water (H2O) and oxygen gas (O2).
• A positive result is indicated by the formation of bubbles when hydrogen peroxide is added to a bacterial colony.
• A negative result shows no bubbles.

Oxidase Test

• Identifies the presence of cytochrome c oxidase, the last enzyme in the electron transport chain.
• This enzyme transfers electrons to the final electron acceptor.
• A positive result is a purple color change on the filter paper disc after adding the oxidase reagent.
• A negative result shows no color change.

DNAse Test

• Determines the ability of bacteria to produce and secrete DNase, an enzyme that breaks down DNA.
• Uses DNase media containing DNA and an indicator like methylene blue.
• A positive result is a clear halo around the bacterial growth, indicating DNA digestion.
• A negative result shows no halo.

Esculin Hydrolysis

• Assesses the bacteria's ability to hydrolyze esculin.
• Bile esculin agar is used, which is both selective (bile salts inhibit certain bacteria) and differential.
• A positive result is a blackening of the media.
• A negative result shows no color change (media remains brown).

Motility Test

• Determines if bacteria have flagella and are motile.
• Uses a less dense agar in a test tube.
• Inoculation is done by stabbing the media with a needle.
• A positive result shows growth away from the stab line.
• A negative result shows growth concentrated along the stab line.