Cultural Characteristics of Bacteria and viruses

Question 1

What is the purpose of growth media in microbiology?

Answer 1

To study and grow microorganisms under controlled laboratory conditions.

Question 2

Culture

Answer 2

A nutrient material prepared for the growth of microorganism in a laboratory

Question 3

Inoculum

Answer 3

Microbes that are introduced into a culture medium to initiate growth

Question 4

Properties of Agar

Answer 4

-Can only be degraded by a few microbes, it remains solid
-Liquefies at 100°C
-Usuall containd in petri dishes or test tubes
-Test tube are called slants

Question 5

Slants

Answer 5

When the tube is held at an angle so that a large surface area for growth is available

Question 6

What are the three main types of media based on consistency?

Answer 6

Liquid, semi-solid, and solid media.

Question 7

What is broth in the context of liquid media?

Answer 7

A transparent fluid made from meat extract or peptone used to culture bacteria.

Question 8

Name an advantage of liquid media.

Answer 8

Allows the growth of bacteria in large volumes, useful for preparing vaccines.

Question 9

What are the advantages of solid media?

Answer 9

Allows study of colony morphology and helps isolate pure colonies.

Question 10

What is simple media also known as?

Answer 10

Basal media.

Question 11

What is complex media?

Answer 11

Media with added nutrients for special growth purposes.

Question 12

What is synthetic media?

Answer 12

Media with a precisely defined chemical composition.

Question 13

What is enriched media?

Answer 13

Provides nutrients and the environmental condition that favors the growth of particular microbes

Question 14

Example of enrichment media?

Answer 14

Tetrathionate broth.
inhibit coliforms and allow typhoid paratyphoid bacilli to grow freely

Question 15

What is selective media?

Answer 15

Suppresses the growth of unwanted bacteria and encourages the development of desired microbes

Question 16

Example of selective media?

Answer 16

MacConkey agar.
Used to isolate & distinguish between Gram-negative enteric rods. MacConkey agar contains bile salts and crystal violet that inhibit Gram positive bacteria but allow the growth of Gram negative bacteria.

Question 17

What is differential media?

Answer 17

Media that distinguishes between colonies of microbes on the same media

Question 18

Example of differential media?

Answer 18

Blood Agar
Differentiates bacteria based on their ability to hemolyze (break down) red blood cells.
ex: Example: Streptococcus pyogenes

Question 19

What are the six parameters to describe colony morphology?

Answer 19

Size, color, texture, form, elevation, and margin.

Question 20

What is the purpose of the Indole test?

Answer 20

To evaluate the organism’s ability to split tryptophan into Indole.
This test is used to help distinguish between Enterobacteriaceae species.

Question 21

What does a positive Indole test look like?

Answer 21

Bright red color at the interface of the reagent and broth.

Question 22

What is the MR test used for?

Answer 22

To detect stable acid end-products from glucose fermentation.
Used to distinguish species of the family Enterobacteriaceae.

Question 23

What color indicates a positive MR test?

Answer 23

Red.

Question 24

What is the VP test used for?

Answer 24

To detect neutral end-products like acetoin from glucose fermentation.
Used to distinguish species of the family Enterobacteriaceae

Question 25

What does a positive VP test look like?

Answer 25

Pinkish-red at the surface.

Question 26

What enzyme does the catalase test detect?

Answer 26

Catalase.
Useful in differentiating between genera

Question 27

What enzyme does the catalase test detect?

Answer 27

Formation of bubbles.

Question 28

What is the Citrate utilization test used for?

Answer 28

To determine if an organism can use citrate as its sole carbon source.
Used to assist in the identification of enterobacteria

Question 29

What color change indicates a positive Citrate test?

Answer 29

Blue.

Question 30

What is transport media used for?

Answer 30

To preserve delicate organisms during transportation to the lab.