Microbiology Agar Media

These flashcards cover key concepts related to agar media used in microbiology, including types of agar, their properties, and their applications in culturing microbes.

What is agar made from?

Agar is a polysaccharide derived from algae or seaweed.

Why do we use agar in microbiology?

Agar prevents microbial movement and allows for qualitative and quantitative assessment of microbial growth.

What happens when agar is heated to 100 degrees Celsius?

It dissolves in water, allowing for nutrient retention.

What temperature must agar cool below to solidify?

Agar needs to cool below 40 degrees Celsius to solidify.

What is LB agar used for?

LB agar is a multipurpose growth medium commonly used to culture E. Coli.

What does TSA stand for in microbiology?

Tryptophase Soy Agar.

What is the primary purpose of blood agar plates?

To differentiate bacteria based on their ability to lyse red blood cells.

What are the three types of hemolysis observed in blood agar?

Alpha hemolysis (partial lysis), Beta hemolysis (complete lysis), and Gamma hemolysis (no lysis).

What type of microbes does Columbia CNA agar selectively culture?

Gram positive microbes.

What is the color of chocolate agar, and why is it named that?

It is dark brown due to lysed blood cells, not made of chocolate.

What distinguishes MacConkey agar plates?

They differentiate between lactose fermenters and non-fermenters.

What is the significance of lactic acid in lactose fermentation?

It lowers the pH, leading to color changes in the colonies.

What color indicates lactose fermentation on a MacConkey agar plate?

Reddish pink tint.

What does Eosin Methylene Blue agar inhibit?

It inhibits gram positive microbes.

What color does E. Coli produce on an EMB plate, and why?

It produces a metallic green color due to dye absorption.

What is the purpose of Mannitol Salt Agar (MSA)?

To selectively culture gram positive microbes and differentiate between staphylococci strains.

What indicates a pathogenic strain of Staphylococcus on MSA?

Yellow colonies due to mannitol fermentation.

How does the texture and elevation of bacterial colonies vary?

Colonies can be flat, raised, smooth, or have different appearances.

What unique property of agar allows for culturing thermophiles?

Agar remains solid at high temperatures, allowing growth of heat-loving microbes.

What does 'hemolysis' refer to in microbiology?

The disintegration or lysis of red blood cells.