Laboratory Identification of Microorganisms

In creating a slide, why is it necessary to dry cells in air before heat fixing?

Why do many colonies appear pigmented?

What is the importance of Gram-staining unknown specimens?

Are there any bacteria that do not Gram-stain, and if so why not?

Why are endospores difficult to stain?

How do Gram-positive and Gram-negative bacteria protect themselves with their cell walls?

What is catalase and what is its function?

What are the selective and differential agents in mannitol salt agar?

What are the selective and differential agents in Horse Blood Crystal Violet agar?

Which microorganisms does mannitol salt agar select for?

What goes on in a catalase biochemical test?

Why should a catalase test not be performed on bacteria growing in a fresh blood agar?

What are the selective and differential agents in MacConkey agar?

Which organisms do bile salts select for?

What are the selective and differential agents in Rose Bengal Chloramphenicol agar?

What does chloramphenicol select for?

Name a common catalase positive and catalase negative bacterium.

What is the oxidase test?

How does one perform an oxidase test?

Why must the reagent for the oxidase test be made fresh just before the test?

What is the oxidation-fermentation test?

As well as differentiating oxidative/fermentative glucose use, what else can the oxidation-fermentation test be used to determine?

Why is it important to perform a multitude of morphological and biochemical tests on an unknown sample?

How does one perform a spore stain?

What colour do spores appear when stained?

What colour do Pseudomonas aeruginosa colonies appear?

What are the steps of performing a Gram stain?

How do Gram-positive bacteria appear when Gram-stained?

How do Gram-negative bacteria appear after being Gram-stained?