Microbial Growth and Nutrition

Question 1

Why does lag phase exsist?

Question 2

What is the exponential phase?

Answer 2

When DNA growth is maximized.

Question 3

What happens to the rate of reproduction as nutrients are depleted and wastes accumulate?

Answer 3

Decrease

Question 4

What is the stationary phase?

Answer 4

When the # of dying cells equals the # of cells being produced, and the size of the population remains constant.

Question 5

Which cells can stay alive in the stationary phase?

Answer 5

Really resilient, stress tolerant cells.

Question 6

What is the death phase?

Answer 6

Cells die at a faster rate than they are produced. Nutrients are not added and wastes are not removed. (Some cells survive)

Question 7

When dying cells release nutrients and the remaining cells feed off these nutrients, what stage is this?

Answer 7

Long-term stationary phase

Question 8

Does the long term stationary phase happen in a healthy digestive system?

Answer 8

Yes.

Question 9

What is generation time?

Answer 9

The amount of time for a population of cells to double in number.

Question 10

True or False.
E. Coli can multiply very quickly.

Answer 10

True

Question 11

What are the environmental factors affection growth?

Answer 11

1.) Solute concentration/osmosis
2.)pH
3.)Temperature
4.) Oxygen concentration

Question 12

Do halophiles love salty environments?

Answer 12

Yes

Question 13

What is an osmophile?

Question 14

What is a compatible solute?

Question 15

At what pH do acidophiles exsist?

Answer 15

pH 0.0-5.5

Question 16

At what pH do neutrophiles exist?

Answer 16

pH 5.5-8.0

Question 17

At what pH do alkalophiles exist?

Answer 17

pH 8-11.5

Question 18

What happens to proteins at high temperatures?

Question 19

What happens to lipids at cold temperatures?

Question 20

What is the maximum growth temperature?

Question 21

What is the optimal growth temperature?

Question 22

What is the minimum growth temperature?

Question 23

What are most human pathogens?

Answer 23

Mesophiles

Question 24

What organism is oxygen toxic to?

Answer 24

Anarob

Question 25

Which 3 enzymes turn toxic peroxide or superoxide into harmless molecules?

Answer 25

Catalase, peroxidase, superoxide dismutase.

Question 26

What is the catalase test?

Question 27

What is an obligate aerobe?

Answer 27

Have catalase and peroxidase

Question 28

What are obligate anaerobes?

Answer 28

Do not have catalase and peroxidase

Question 29

What are facultative anaerobes?

Question 30

What are aerotolerant anaerobes?

Question 31

What are microaerophiles?

Question 32

What does a liquid thioglycollate growth media identify?

Answer 32

Oxygen requirements

Question 33

What are biofilms?

Answer 33

Microbial communities, that have synergistic relationships among numerous microorganisms, attached to surfaces such as teeth, rocks in streams, showers and implants.

Question 34

What is the sample you are trying to grow?

Answer 34

Innoculum

Question 35

What is the collection of nutrients innoculum can grow on.

Answer 35

Medium

Question 36

What is the liquid media?

Answer 36

Broth

Question 37

What are the cultures visible on solid media?

Answer 37

Colonies

Question 38

What is the basis of all solid media?

Answer 38

Agar

Question 39

What is agar?

Answer 39

complex polysaccharide derived from the cell walls of certain red algae

Question 40

At what temperature does agar dissolve in water? Why is this beneficial?

Answer 40

100 C This doesn't kill most nutrients

Question 41

At what temperature does agar solidify? Why is this beneficial?

Answer 41

40 C The ability to add more temperature-sensitive nutrients before solidifying

Question 42

What is complex media?

Question 43

What is selective media?

Answer 43

Contains substances that either favor the growth of particular microorganisms or inhibit the growth of unwanted ones.

Question 44

Eosin, Methylene Blue, Bile Salts – all kill gram positives but are harmless to gram negatives Increase NaCl to ensure only halophiles grow FIX UP

Answer 44

Selective media

Question 45

What is differential media?

Answer 45

Either the presence of visible changes in the medium or differences in the appearance of colonies help us differentiate among the kinds of bacteria growing on the medium

Question 46

What kind of media is the utilization of RBC's in blood agar an example of?

Answer 46

Differential media

Question 47

Carbohydrate utilization tubes: each tube contains a single kind of simple carbohydrate as a carbon source and the dye phenol red as a pH indicator. What kind of media is this an example of?

Answer 47

Differential media

Question 48

How do we grow anaerobic media?

Answer 48

Stab culture

Question 49

Nutrient agar?

Question 50

What do MacConkey agar do?

Answer 50

They enhance the growth of certain species that can then be distinguished from other species by variations in appearance

Question 51

True or false. Macconkey agar is only selective

Answer 51

False. It can be selective AND differential

Question 52

What are the 8 ways to identify microorganisms?

Answer 52

Shape, margin, elevation, size, texture, appearance, pigmentation, optical property.

Question 53

What 4 places can we take clinical samples to test for microbes?

Answer 53

1.) Skin, accessible membrane, wounds 2.) Blood 3.) Cerebrospinal fluid 4.) Lungs 5.) Other: Intubation, catheter, biopsy

Question 54

What is a streak plate used for?

Answer 54

To isolate the organisms from a mixed population into a pure culture. Inoculum is diluted by streaking it across the surface of the agar plate.

Question 55

What is serial dilution? And when is it used?

Answer 55

It's used for very large populations to isolate the colony and measure the population size.

Question 56

What is membrane filtration? And when is it used?

Answer 56

Used for very small populations. Membrane filter retains samples.b

Question 57

What is turbidity? And when is it used?

Answer 57

Used indirectly for large populations. You're not counting at all.