Lecture 9

Question 1

How is growth measured for bacteria

Answer 1

Increase in the number of individuals

Question 2

What is binary fission?

Answer 2

When one cell splits into two cells

Question 3

How often doe binary fission happen?

Answer 3

Once every 20 minutes

Question 4

T of F- The growth curve is not logarithmic

Answer 4

False, it is logarithmic

Question 5

T or F- The growth curve count all cells

Answer 5

False, it only counts viable cells

Question 6

What are the major phases of the growth curve?

Answer 6

1. Lag Phase
2. Log Growth Phase
3. Stationary Phase
4. Death Phase

Question 7

Define the lag phase

Answer 7

It is the time that it takes for the organism to get used to its environment, has an increase in metabolism, and little to no cell division

Question 8

Define the log growth phase

Answer 8

It is the point where the population actually starts doubling

Question 9

When is a culture a young culture?

Answer 9

During the log growth phase

Question 10

Define the stationary phase

Answer 10

Carrying capacity of the enviroment, with an equal number of cells dying as are dividing

Question 11

When is a culture a mature culture?

Answer 11

In the stationary phase

Question 12

Define the log death phase

Answer 12

Large number of individuals dying

Question 13

When is a culture mature?

Answer 13

During the log death phase

Question 14

What does cultural enumeration mean?

Answer 14

it means that you are growing out the colony

Question 15

What is the CFU?

Answer 15

The colony forming unit, which is a single cell that will grow out into a colony

Question 16

What is the name for the single cell that grows out into a colony?

Answer 16

The colony forming unit (CFU)

Question 17

What are the direct plating methods?

Answer 17

1. Colony Count Plating Method
2. Enumeration
3. Membrane Filter Method

Question 18

Explain the colony count plating method

Answer 18

A serial dilution wherein you take 1mL of sample and dilute it into 9mL of water/saline. You repeat this process until the number of colonies on a plate is between 25-250

Question 19

What does TNTC mean and when is it used?

Answer 19

‘Too numerous to count’, used where there are more than 250 colonies on a plate

Question 20

Why is load important?

Answer 20

Load is important because the higher load you have (more bacteria) the more medication you need to give to the patient

Question 21

Why do we do serial dilutions?

Answer 21

To find out the load of the bacteria, which in turn tells us how much medication the patient needs

Question 22

What is the difference between the enumeration method and the colony count plating method?

Answer 22

The enumeration method only takes .1mL from the flask to determine the growth factor of the colony. CCP uses 1mL

Question 23

Define Membrane filter method

Answer 23

Used mostly for water samples that you would not expect much bacteria in. A filter membrane with small holes is placed to catch remaining bacteria

Question 24

How large are the holes in the filter of the membrane filter method?

Answer 24

About .2um, which results in clogging with highly contaminated samples

Question 25

Is the membrane filter method a direct or indirect method?

Answer 25

Direct

Question 26

What are the indirect methods for cultural enumeration?

Answer 26

1. Most probable number

Question 27

Describe the Most Probable Method process

Answer 27

Get a major sample of bacteria and place 10mL in 5 tubes, 1mL in 5 tubes, and .1mL in 5 tubes. Inside each tube is a secondary tube that will trap the gasesm allowing you to calculate the number of bacteria in the original sample

Question 28

Do you count the individual colonies in the Most Probable method?

Answer 28

No

Question 29

How many tubes total are used in MPN method?

Answer 29

15, 5 with 10mL, 5 with 1mL, and 5 with .1mL

Question 30

Why do you use to many tubes in the MPN method?

Answer 30

To ensure accuracy

Question 31

What is the MPN method most comonly used for?

Answer 31

used to test for coliforms, such as e.coli, in water

Question 32

What test would you use to test for coliforms?

Answer 32

The Most Probable Number test (MPD)

Question 33

Name the non-cultural enumeration methods

Answer 33

``` Direct: 1. Cytometer 2. Coulter counter Indirect: 1. Total volume 2. Turbometric ```

Question 34

What are the direct noncultural enumeration methods?

Answer 34

1. Cytometer | 2. Coulter counter

Question 35

Is the MPN method direct or indirect?

Answer 35

Indirect

Question 36

Name the direct non-cultural enumeration methods

Answer 36

1. Total volume | 2. Turbometric

Question 37

Describe the cytometer count method

Answer 37

It is the gold standard for non-enumeration, and use you a gridded slide and count the number of bacteria that grow on it. It need to be standardized before use, and repeated if any of the count differ by 10% from other counts

Question 38

Cytometer is best used for what kind of samples?

Answer 38

Blood samples

Question 39

Describe the Coulter count method

Answer 39

A long electronic beam passes through a tube and is broken every time a bacteria passes through it. This needs to be standarized before use using the cytometer count method

Question 40

What method do you use to standardize the coulter count method?

Answer 40

The cytometer count method

Question 41

Describe the total volume method

Answer 41

You place the sample in a centrifuge, which results in the solids sitting at the bottom of the tube, can be done in 5 minutes, and need to be standardized using the colony count plate method

Question 42

What do you use to standardize the total volume method?

Answer 42

The colony count plate method

Question 43

What is the total volume method commonly used for?

Answer 43

Beer

Question 44

How long does a total volume method normally take?

Answer 44

About 5 minutes

Question 45

Describe the turbometric method

Answer 45

You shine a light through your sample and measure how much is absorbed. The more that is absorbed, the more bacteria there is. This needs to be standardized

Question 46

You are using the turbometric method, and find that a lot of light shines through your sample. What does this mean?

Answer 46

It means you don't have a lot of bacteria in that sample

Question 47

The the total volume method a cultural enumeration method or a noncultural enumeration method?

Answer 47

noncultural enumeration method

Question 48

How can you tell how much bacteria you have in a most probable number method?

Answer 48

Each tube has a secondary tube inside of it that captures the CO2 produced by the bacteria in the sample