Microbial Growth/Development

Question 1

Two most common kinds of lab culture media

Answer 1

Complex & Minimal defined

Question 2

What is Complex or Rich media?

Answer 2

Contains non-defined components
- LB medium has:
– Bactotyptone (protein), Bacto yeast extract, NaCl (osmolarity balance), pH of 7

Question 3

What is Minimal defined media?

Answer 3

Contains known components
- M9 medium has:
– Glucose, NaCl, MgSO4, CaCl2….. , pH of 7

Question 4

Most common way to determine/measure viable cells?

Answer 4

Staining & measuring colony forming units (cfu)

Question 5

What is a batch culture?

Answer 5

A set amount of time that a bacteria is grown to obtain results

Question 6

Define Lag phase

Answer 6

No growth - in prep for growing

Question 7

Define Log phase

Answer 7

Exponential phase - growth approximates an exponential curve

Question 8

Define Stationary phase

Answer 8

Cells stop growing but are not dying just surviving

Question 9

Define Death phase

Answer 9

Cells die

Question 10

Can bacteria be grown in batch culture of liquid?

Answer 10

Yes

Question 11

What is doubling time?

Answer 11

Calculated from exponential growth in the log phase (denoted by ‘g’)

Question 12

What is continuous culture?

Answer 12

Constantly adding fresh and drawing off old media to maintain exponential growth

Question 13

What organisms thrive in high temperatures?

Answer 13

Thermophiles (& Extreme thermophiles)

Question 14

What organisms thrive in (relatively) normal temperatures?

Answer 14

Mesophiles

Question 15

What organisms thrive in colder temperatures?

Answer 15

Psychrophiles

Question 16

What is the term for organisms that have adapted to various pressures?

Answer 16

Barophile

Question 17

What is the term for organisms that have adapted to various tonicity conditions?

Answer 17

Halophiles

Question 18

Do most prokaryotes keep high or low internal osmolarity? Why?

Answer 18

High - to maintain turgor pressure to allow growth

Question 19

How do cells act in a hypotonic environment?

Answer 19

Cell wall keeps the cell shape, Inclusion bodies maintain by holding molecules in the cell, Channels to expel excess solute

Question 20

How do cells act in a hypertonic environment?

Answer 20

Synthesis and uptake of solutes

Question 21

Which organisms thrive in an acidic environment?

Answer 21

Acidophiles

Question 22

Which organisms thrive in a neutral environment?

Answer 22

Neutrophiles

Question 23

Which organisms thrive in a basic (alkaline) environment?

Answer 23

Alkaliphiles

Question 24

Why does the cytoplasmic pH need to remain neutral?

Answer 24

To allow for function of transporters and enzymes

Question 25

What is the main source of energy for work in neutrophiles?

Answer 25

Proton Gradient

Question 26

What is the main source of energy for work in alkaliphiles?

Answer 26

Na+ gradient (some) & H+

Question 27

What is an obligate aerobe?

Answer 27

Cannot grow/live without oxygen

Question 28

What is a strict anaerobe?

Answer 28

Does not use oxygen at all - uses fermentation

Question 29

What is an aerotolerant anaerobe?

Answer 29

Can grow in either extreme (with or without oxygen)

Question 30

What is a facultative anaerobe?

Answer 30

Has metabolic pathway for both, but has more success aerobically

Question 31

What is a microaerophile?

Answer 31

Will grow in low oxygen but not in high

Question 32

What damages protein, DNA, enzymes and membranes?

Answer 32

O2 and Reactive Oxygen Species

Question 33

Which enzymes destroy ROS?

Answer 33

Superoxide dismutase, peroxidase, catalase

Question 34

What are the most common ways to manipulate the environment to control microorganisms?

Answer 34

Autoclaving, pasteurization, dehydration, salt, sugar

Question 35

T/F - Different regions of biofilms can have different growth stages

Answer 35

True

Question 36

Can there be more than one species in a biofilm?

Answer 36

Yes, the species can either cooperate or protect the other

Question 37

T/F - Treating cells in a biofilm is easy

Answer 37

False - cells can survive antibiotics better within a biofilm

Question 38

What is Bacillus subtilis?

Answer 38

soil bacteria species that can generate multiple cell types

Question 39

What are the 4 types of Bacillus subtilis cells?

Answer 39

Motile cells, biofilm (matrix producing), sporulating cells, competent cells

Question 40

What is a spore?

Answer 40

Dormant and highly heat resistant forms of bacteria that can grow and divide w/o nutrition

Question 41

What is a Persister cell?

Answer 41

Will survive lethal doses of antibiotics b/c of a physiological change rather than a genetic one

Question 42

What is Caulobacter crescentus?

Answer 42

An aquatic bacterial species with a programmed development cycle that produces 2 cell types

Question 43

What are the 2 cell types in Caulobacter crescentus?

Answer 43

Stalk & hold-fast, flagella

Question 44

What kinds of biofilms to each of the caulobacter species form?

Answer 44

Flagella - monolayer Stalk - mushroom (multi-layer)