Microbial Growth in Extreme Environments

Question 1

What kind of environmental conditions do most organisms prefer?

Answer 1

Neutral.

Question 2

What are common factors that influence environmental conditions?

Answer 2

1. pH.
2. Temperature.
3. O2 concentration.
4. Pressure.
5. Solute concentration.
   *Always fluctuating

Question 3

What are extremophiles?

Answer 3

Microorganisms that permanently live in environments that have one or more extreme environmental conditions.
*Some may even require extreme conditions for optimal growth.

Question 4

What are some common mechanisms extremophiles use to survive?

Answer 4

1. Synthesis of specialized enzymes and proteins.
2. Altering genomic material (More G-C than A-T).
3. Altering membrane composition.
4. Opening and/or closing channels to acquire and/or remove substances to balance the intracellular environment.

Question 5

What extremophiles live in environments with high or low osmotic concentrations relative to the extremophile called?

Answer 5

1. Osmophiles.
2. Halophiles.

Question 6

What is the typical outcome for organisms in a high or low osmotic concentrations relative to the organism environment?

Answer 6

The cell will crenate due to the efflux of water or lyse due to the influx of water.

Question 7

How do extremophiles in high or low osmotic concentrations relative to the extremophile environments adapt?

Answer 7

1. Channels in the cell membrane open to allow solute to leave, increasing internal osmotic concentration.
2. Acquire compatible solutes.
3. Have a cell wall and other features that require a high salt concentration.

Question 8

What are extremophiles that live in high of low pH environments called?

Answer 8

1. Alkaliphiles.
2. Acidophiles.

Question 9

What is the typical outcome for most organisms in a high or low pH environment?

Answer 9

pH of the cytoplasm matches that of the environment, causing cell death.

Question 10

How do extremophiles in high or low pH environments adapt?

Answer 10

They utilize mechanisms for maintaining a neutral cytoplasm such as: proton exchange, synthesis of specialized proteins, and production of waste products to balance environmental waste.

Question 11

What are extremophiles that live in low or high temperature environments called?

Answer 11

1. Psychrophiles.
2. Thermophiles.

Question 12

What is the typical outcome for most organisms in a low or high temperature environment?

Answer 12

They often die due to microbes being unable to regulate their internal temperature and their enzymes not functioning.

Question 13

How do extremophiles that live in low or high temperature environments adapt?

Answer 13

Utilize means to stabilize membrane and proteins.

Question 14

What are extremophiles that live in high pressure environments called?

Answer 14

Barophiles.
*Typically most organisms are not in a high pressure environment, so what is normal and adaptation mechanisms do not need to be discussed.

Question 15

What are extremophiles that live in environments with a high or low concentration of O2 called?

Answer 15

1. Obligate aerobe.
2. Obligate anaerobe.
3. Facultative anaerobes.

Question 16

What is the typical outcome for AEROBIC organisms in environments with high or low O2?

Answer 16

Utilize O2 for metabolic processes to generate energy if present. If not present, they die.

Question 17

What is the typical outcome for ANAEROBIC organisms in environments with high or low O2?

Answer 17

Thrive in low O2 or O2-free environments by employing other means of getting energy.

Question 18

What is the typical outcome for FACULTATIVE organisms in environments with high or low O2?

Answer 18

Do better in the presence of O2, but can get by in an low O2 or O2-free environment.

Question 19

How do extremophiles that live in high or low O2 environments adapt?

Answer 19

1. Obligate anaerobes will associate with facultative anaerobes that will remove O2 from the environment.
2. Utilize enzymes that scavenge for and neutralize ROS byproducts.

Question 20

What does growth in different O2 concentration depend upon?

Answer 20

1. Metabolic processes.
2. Electron Transport Chain.
3. Terminal Electron Acceptor used.

Question 21

What are the 4 toxic products that oxygen can be turned into when it enters into cellular reactions?

Answer 21

1. Singlet oxygen.
2. Superoxide ion.
3. Hydrogen peroxide.
4. Hydroxyl radical.

Question 22

What is a singlet oxygen (O)?

Answer 22

An extremely reactive molecule that can damage and destroy a cell by oxidizing membrane lipids.

Question 23

What is a superoxide ion (O2-)?

Answer 23

A highly reactive molecule.

Question 24

What effect does hydrogen peroxide (H2O2) have on cells?

Answer 24

Toxic to cells and used as a disinfectant.

Question 25

What is a hydroxyl radical (OH-)?

Answer 25

Also highly reactive.

Question 26

How do microbes avoid the toxic products of oxygen in cellular reactions?

Answer 26

Specialized enzymes.
*Two-step process

Question 27

What enzyme is used to convert superoxide ions into hydrogen peroxide?

Answer 27

Superoxide dismutase.

Question 28

What enzyme is used to convert hydrogen peroxide into water and oxygen?

Answer 28

Catalase.

Question 29

How are microbial environments described?

Answer 29

Complex, constantly changing.
*Exposes microorganisms to overlapping gradients of nutrients and environmental factors.

Question 30

Can microbial organisms include macroorganisms?

Answer 30

Yes.

Question 31

What is an oligotrophic environment?

Answer 31

Low nutrient.
*Most microbes live in this kind of environment.

Question 32

What kind of responses to starvation and environmental stress have microbes evolved?

Answer 32

1. Morphological changes (Endospore formation).
2. Enter stationary phase of growth curve.
3. Can use cellular components as nutrients.
4. Numerous genes and proteins that help.
5. Viable but not culturable state.