Lecture 5 Microbial Growth And Physiology

Question 1

Boiling is what temperature and how long

Answer 1

•100 degrees celcius
•30 minutes

Question 2

Autoclave is at what temperature and for how long

Answer 2

120 degrees celcius
30 minutes

Question 3

Dry heat is at what temperature and for how long

Answer 3

•150 degrees celcius
•120 minutes

Question 4

What process do bacteria divide by

Answer 4

Binary fission

Question 5

When the chromosome divides during binary fission what does it produce

Answer 5

Two identical copies

Question 6

Is Bacterial growth described as exponential

Answer 6

Yes the generation time (time for bacterial mass to double) can be as fast as 20 minutes

Question 7

What temperature does agar melt as

Answer 7

100 degrees celcius

Question 8

What temperature does agar solidify at

Answer 8

40 degrees celcius

Question 9

How is Agar sterilised

Answer 9

By Autoclaving

Question 10

What do bacteria grow as on agar

Answer 10

As Colonies

Question 11

How many cells/ml for growth in a liquid medium

Answer 11

10^9 cells/ml

Question 12

For growth in a liquid medium what is position for incubation

Answer 12

Standing or Agitated

Question 13

What are the growth phases of a Bacterial Culture

Answer 13

•Lag
•Log
•Stationary
•Death

Question 14

Describe each of the growth phases of a Bacterial Culture

Answer 14

•Lag
Adaption
•Log
Cells multiply at the maximum rate
•Stationary
Lack of nutrients and build up of toxic metabolic intermediates means multiplication is balanced by cell death
•Death

Question 15

Describe the two direct measurements of Bacterial growth

Answer 15

•Total Cell Count
Using microscope and counting chamber

•Total Viable Count
Cells in culture are diluted and spread on nutrient agar plates

Question 16

Total viable count is a serial ___ -fold dilution

Answer 16

10

Question 17

Name the indirect measurement of bacterial growth

Answer 17

•Turbidity
•Cloudiness
•Measure live and dead cells

Question 18

What is the nm of a filter or prism in a Spectrophotometer

Answer 18

•540nm

Question 19

In a Chemostat culture what is cell density controlled by

Answer 19

Nutrient Concentration

Question 20

What is Growth rate controlled by in a Chemostat culture

Answer 20

By the flow rate of nutrient

Question 21

What does Growth require

Answer 21

•Energy
•Building blocks required for construction of cellular machinery
•Appropriate environmental conditions

Question 22

Name the nutrient requirements for Growth

Answer 22

– Water
– Carbon (carbohydrate)
– Nitrogen (protein)
– Inorganic salts Iron - siderophores – Oxidation of organic compounds
– (carbohydrates, lipids, proteins)

Question 23

What temperature is required for Growth

Answer 23

20-110 degrees celcius

Question 24

What pH is required for Growth

Answer 24

4.0-9.0

Question 25

What type of Atmosphere for growth

Answer 25

O2/ No O2

Question 26

What is Energy derived from

Answer 26

The enzymatic breakdown of organic substrates (carbohydrates,lipids or proteins) in a process called CATOBOLISM

Question 27

What is Energy generated from CATABOLISM used to synthesise

Answer 27

Cellular constituents in a process called ANABOLISM

Question 28

Catabolism + Anabolism =

Answer 28

Metabolism

Question 29

Other than carbohydrates,lipids and proteins where else can bacteria derive energy from

Answer 29

•Plastic •Rubber •Toxic compounds like Phenol

Question 30

What are Auxotrophs

Answer 30

The ability of individual bacterial species to produce their own cellular components will dictate its nutritional requirement

Question 31

Obligate Aerobes grow only in the presence of what

Answer 31

O2

Question 32

Obligate Anaerobes grown only in the absence and are killed by

Answer 32

O2

Question 33

Facultative Anaerobes grow in the presence and absence and of

Answer 33

O2

Question 34

What are Psychrophile bacteria

Answer 34

•Cold loving bacteria •10-20 degrees Celsius

Question 35

What are Mesophile bacteria

Answer 35

•Human body temperature •Pathogens •Opportunists •20-40 degrees Celsius

Question 36

What are Thermophile Bacteria

Answer 36

•Heat loving •>60 degrees Celsius

Question 37

Some bacteria can grow / survive in what ph

Answer 37

•acid •alkali