Biochemical Testing

What occurs in a Catalase test?

• Hydrogen peroxide (H2O2) forms

• As a by-product of aerobic metabolism

Which enzyme breaks down H2O2 into _

• Catalase

• Breaks down 2H₂O₂ → 2H₂O (*water) + O₂ (*oxygen)

Test used to detect the presence of the enzyme Catalase

Catalase Test

What does Catalase Test help distinguish 

• Gram+ cocci: Staphylococci and Streptococci

What does the presence of bubbling indicate?

Enzyme Catalase is present

If Catalase Test Positive, could be what 2 bacteria?

• Staphylococcus

• Micrococcus

If Catalase Test Negative, could be what 2 bacteria?

• Enterococcus

• Streptococcus

The Oxidative Test detects the presence of _

bacteria that use Enzyme Cytochrome C Oxidase in cellular resp 

What does Oxidative Test help distinguish 

Gram Negative Bacilli

2 functions of Cytochrome C. oxidase

• Final enzyme used in the electron transport chain

• Transfers electrons from a molecule to oxygen

The Oxidase Reagent is a _ 

Chromogenic reducing agent- chemical that develops color as

oxidized

What reacts w cytochrome c oxidase & what color does it turn it 

• Oxidase Reagent 

• turns C Oxidase purple 

If Oxidase Test Positive, could be what 2 bacteria?

• Pseudomonadaceae

• Neisseria

If Oxidase Test Negative, could be what bacteria & 2 examples?

• Enterobacteriaceae:

  • Escheriichia coli

  • Serratia marcescens

What can’t be used in Oxidase test & why 

• metal loop to transfer bacteria bc:

• metal will react with oxidase reagent & give false + result

  • *result needs to be seen within 10s.