Differentiating Bacteria via Media and cell counting

Question 1

Unique biochemical properties allow us to distinguish different bacteria by giving them

Answer 1

certain nutrients

Question 2

What is selective media used for?

Answer 2

To isolate certain types of bacteria

Question 3

Differential media distinguish among ______ and __________related groups of organisms

Answer 3

morphologically and biochemically

Question 4

What is enriched media?

Answer 4

Media that have been supplemented with highly nutritious materials to help cultivate hard to grow bacteria

Question 5

Selective media have properties that inhibit the growth of certain types of bacteria. Permitted organisms are able to grow due to their

Answer 5

unique biochemical properties

Question 6

What are some examples of selective media

Answer 6

Antibiotic Agar
Phenylethyl Alcohol Agar
Crystal Violet Agar
7.5% Sodium Chloride Agar

Question 7

Which antibiotic is added to the nutrient agar plate to make the antibiotic agar and which types of bacteria will grow?

Answer 7

An antibiotic such as ampicillin (a penicillin derivative) is added to the nutrient agar plate

Only bacteria that are resistant to ampicillin will grow

Question 8

This media Isolates most gram-positive organisms

Answer 8

• Phenylethyl alcohol agar

Phenylethyl alcohol is partially inhibitory to gram-negative organisms
Gram-negative organisms may still grow, but there will be fewer and smaller colonies than gram-positive organisms

Question 9

Which media is used for gram-negative organisms?

Answer 9

Crystal violet agar

Crystal violet inhibits growth of gram-positive bacteria

Question 10

7.5% Sodium Chloride Agar media Inhibits most organisms except

Answer 10

• halophilic ones
• Useful for isolating Staphylococcus species

Question 11

Halophilic organisms grow well environments

Answer 11

-high salt content.
-Halophilic literally translates to salt-loving

Question 12

What does differential media allow for and give examples.

Answer 12

• Differential media allows for different bacterial have unique morphological characteristics based on their biochemical properties
• Differential media are often also selective

Examples:
Mannitol salt agar
MacConkey agar
Eosin-methylene blue (EMB) agar

Question 13

Manitol salt agar is made up of? What does it favor? What does the pH indicator detect?

Answer 13

• 7.5 NaCl
• favors staphylococcus
• Ph indicator to detect acid produced from fermentation

Question 14

What is manitol agar used for? What color does the species that can ferment mannitol become?

Answer 14

• Used to differentiate species of staphylococci
• yellow