Citrate Biochemical Test Overview

What is the purpose of the Citrate Test?

To determine if bacteria can produce citrate permease to move citrate into the cell and citrase to break down citrate.

How is citrate moved into the bacterial cell?

Citrate is moved into the bacterial cell via citrate permease.

What is the reaction catalyzed by citrase?

Citrate is broken down into pyruvate.

What are the substrates involved in the Citrate Test?

Citrate and ammonium phosphate.

What enzymes are produced by bacteria after inoculation in the Citrate Test?

Citrate permease and citrase.

What is the role of citrate permease in bacteria?

It makes the bacteria more permeable to citrate, allowing citrate to be moved into the cell.

What is the indicator used in the Citrate Test?

Bromothymol blue.

What color change occurs in bromothymol blue due to pH changes?

It changes from forest green (acidic) to royal blue (basic).

What products are formed when citrase breaks down citrate?

Pyruvate.

What products are formed when bacteria use ammonium phosphate?

Ammonia and ammonium hydroxide.

What effect does ammonia production have on pH in the Citrate Test?

It turns the pH basic, resulting in a color change of bromothymol blue.

What indicates a positive result in the Citrate Test?

A royal blue color due to a basic pH from ammonia production.

What does a positive result indicate about the bacteria?

The bacteria can produce citrate permease and citrase, allowing them to utilize citrate and ammonium phosphate.

What indicates a negative result in the Citrate Test?

A forest green color due to no change in pH.

What does a negative result indicate about the bacteria?

The bacteria cannot produce citrate permease or citrase.

What happens to the color of bromothymol blue if ammonia is not produced?

The color remains forest green.

What is the significance of pyruvate in the Citrate Test?

It is the product formed when citrase breaks down citrate.

What happens to the pH when bacteria continue to grow and use ammonium phosphate?

The pH becomes basic due to ammonia production.

What color does bromothymol blue turn in a basic environment?

Royal blue.

What is the initial color of bromothymol blue before inoculation?

Forest green.