Lecture 6 : Extremophiles

Question 1

What are the four factors that contribute to extreme habitat conditions?

Answer 1

1. temperature
2. pressure
3. salinity
4. pH
5. radiation

Question 2

What characteristics make up the Marine Hydrothermal vents at the sea floor?

Answer 2

• white smokers
• black smokers
• seawater = 2C
• sulfidic environments
• high pressure >300 atm (100 mPa)

Question 3

What causes the color in Black Smokers?

Answer 3

Black color is caused by the presence of iron and sulfur.
* when the iron monosulfide solidifies, it creates the black chimneys
* hotter

Question 4

What causes the color in White Smokers?

Answer 4

White color is caused by barium, calcium, and silicon.
* cooler

Question 5

What are the characteristics of terrestrial sulfuric environments?

Answer 5

• fumaroles, geysers
• hot springs
• temperature up to 100C
• pH 1-12

Question 6

What are the 2 MAIN thermophilic microbes?

Answer 6

• thermophiles: 50-80C
• hyperthermophiles: >80C

Question 7

What thermophilic microbes fall under Archaea and what kind of trophs are they?

Answer 7

• methanopyrus: anaerobic chemolithoautotrophs
• pyrodictium: sulfur chemolithoautotrophs
• pyrococcus: sulfer hetertrophs

Question 8

What thermophilic microbes fall under Bacteria and what kind of trophs are they?

Answer 8

• thermotoga: heterotrophs
• aquifex: sulfer chemolithoautotrophs
• thermus: aerbic heterotrophs

Question 9

What habitats are Psychrophiles and Psychrotolerants found at?

Answer 9

Deep ocean, sea ice, Antarctica

Question 10

What is the optimal temperature for Psychrophiles?

Answer 10

15-20C

Question 11

What is the optimal temperature for Psychrotolerants?

Answer 11

> 20C

Question 12

What are the 4 temperature adaptions?

Answer 12

1. Lipids
   - maintain structure
2. GC Content
   - encodes thermostable amino acids
3. Heat/Cold Shock Proteins
   - facilitate protein folding
4. Enzyme Activity
   - enzyme variability allows for increased functional ability

Question 13

Thalassohaline

Answer 13

derived from seawater

Question 14

Athalassohaline

Answer 14

salts derived from geology of terrestrial habitats
ex. dead sea, great salt lake, Mg2+ rich

Question 15

Halophilic microbes

Answer 15

Eukaryotic Algae: Dunaliella aka green algae
Archaea: Haloarcula, Halorubrum, Haloquadratum
Bacteria: Halomonas, Salinivibrio Cyanobacteriaq

Question 16

What are the characteristics of halophile physiology?

Answer 16

1. Na+ stabilizes cell wall
2. Compatible solutes
   
   • archaea: 5M K+ actively pumped in from water
   • bacteria: glycine-betaine, trehalose synthesized
3. Bacteriorhodopsin pigment
   
   • under low oxygen conditions
   • membrane protein - conjugate to a retinal molecule (carotenoid-like) that absorbs light
4. Carotenoids
   
   • protects cell DNA from UV induced radicals

Question 17

What are the three acidic habitats?

Answer 17

1. Hot springs
2. Volcanic Soils
3. Mining

Question 18

What are the acidophilic microbes?

Answer 18

1. Fungi - more acidophilic than prokaryotes
2. Algae - cyanidium and zygogonium
3. Archaea - picrophilus : pH 0.7, sulfolobus: pH <2.0
4. Bacteria - thiobacillus: pH 2-4 , Leptospirillum

Question 19

What are the 3 Alkaliphilic habitats?

Answer 19

Soda Lakes. East Africa Rift, Mono Lake all with a pH ~ 10

Question 20

What archaea are found in alkaliphilic habitats?

Answer 20

Natronobacterium, Natronococcus

Question 21

What bacteria are found in alkaliphilic habitats?

Answer 21

Cyanobacteria. Gram positives like Bacillus and Clostridium

Question 22

How do acidophilic/alkaliphilics generate proton motive force?

Answer 22

Na+ is substituted for some purposes in both

Question 23

What is the internal pH of acido/alkaphilics?

Answer 23

Neutral but may be as ;pw as 2-3 and upwards of 8-9

Question 24

What do protos do in the membranes of acido/alkaphilics?

Answer 24

Stabilize membranes