Isolation and Cultivation of Microorganisms

Question 1

List

Essential elements as a percent of cell dry weight

7

Answer 1

1. Carbon
2. Oxygen
3. Nitrogen
4. Hydrogen
5. Phosphorus
6. Sulfur
7. Selenium

Question 2

Composition of a Cell

4 | Bonus: Percentages

Answer 2

Water: 70-80% wet weight
Proteins: 55% dry weight
RNA: 20.5% dry
DNA: 3.1% dry

Question 3

Main kinds of sources

2

Answer 3

Carbon
Nitrogen

Question 4

Kinds of microorganisms (carbon sources)

2

Answer 4

Hetotrophic
Autotrophic

Question 5

• Microorganisms that require organic compounds as their source
• Ex. Glucose, lactose

Answer 5

Heterotrophic microorganisms

Question 6

• Microorganisms that use CO2 as carbon source
• no need to provide carbon source in medium
• CO2 is reduced to glucose

Answer 6

Autotrophic microorganisms

Question 7

Differentiate

Carbon Sources vs Nitrogen Sources

Answer 7

Carbon
* Necessary for synthesis of new cell materials

Nitrogen
* Necessary for protein synthesis and amino acid production

Question 8

What do trace elements and vitamins do?

Answer 8

• Act as cofactors in enzymatic reactions
• Some pathogens obtain vitamins from host
• Ex: Cu, Co, Zn, Mg, folic acid, vitamin B12, vitamin K

Question 9

List

Types of Culture Media

2

Answer 9

1. Defined
2. Complex

Question 10

• Media that contains precise amounts of highly purified organic/inorganic components
• Usu. colorless

Answer 10

Defined Media

Question 11

• Media that contains dehydrated digests of animal, plant, or microbial products
• Usu. yellow colored
• Contains imprecise nutritional composition
• Eg casein, yeast, beef soybeans

Answer 11

Complex

Question 12

Why is there glucose in culture media?

Answer 12

• organisms can utilize glucose as a carbon source
• whether it is defined/complex

Question 13

Kinds of Complex Media

5

Answer 13

1. Enriched medium
2. Selective Medium
3. Differential medium

Question 14

Complex base w/ addtl nutrients (e.g. blood, serum, etc.)

Answer 14

Enriched medium

Question 15

List

Examples of Enriched Medium

2

Answer 15

1. Chocolate agar
2. Blood plate agar

Question 16

• For isolating Neisseria (causative agent of gonorrhea) and H. influenzae (causative agent of influenza)
• Contains lysed (aka butas na) red blood cells

Answer 16

Chocolate agar

Question 17

• For isolating S. haemolyticus
• White area indicates degradation of red blood cells
• Contains whole red blood cells

Answer 17

Blood plate agar

Question 18

What species does chocolate agar isolate?

Answer 18

Neisseria (causative agent of gonorrhea) and H. influenzae (causative agent of influenza)

Question 19

What species does blood plate agar isolate?

Answer 19

S. haemolyticus

Question 20

Contains compounds that inhibit the growth of one bacterial group but supports the growth of another

Answer 20

Selective Medium

Question 21

Selective Medium
Identify the component of:
1. MacConkey Agar MAC
1. Eosin Methylene Blue EMB
1. Mannitol Salt Agar MSA

Answer 21

1. MAC: Bible Salts
2. EMB: Eosine & methylene blue
3. MSA: 7.5% NaCl

Question 22

What bacteria do MAC EMB and MSA inhibit? (G+ or G-)

Answer 22

MAC: G+
EMB: G+
MSA: G-, salt-sensitive G+

Question 23

Differential Medium
Identify the component of:
1. MacConkey Agar MAC
1. Eosin Methylene Blue EMB
1. Mannitol Salt Agar MSA

Answer 23

1. MAC: Neutral red
2. EMB: Methylene Blue
3. MSA: Phenol Red

Question 24

What reaction does MAC/EMB/MSA detect/differentiate?

Answer 24

1. MAC: Lactose fermentation
2. EMB: Lactose fermentation
3. MSA: Mannitol fermentation

Question 25

Contains an indicator that determines if a biochemical reaction occurred

Answer 25

Differential medium