Hyperthermophiles, Acidophiles (Extreme environment II)

Question 1

What colours does each major taxon produce in a hot spring?

Answer 1

Red- Archae
Blue- Bacteria
Light green- Algae
Brown- Fungi
Yellow- Protozoa
Dark green- plants
Animals- Purple

Question 2

Whats a Thermophile? Examples?

Answer 2

• Organism that likes a temperature of 60 degrees

- Geobacillus

Question 3

Whats a Acidophile?

Answer 3

Organism that can withstand acidic environments

Question 4

Studies of thermal habitats have revealed what?

Answer 4

• Prokaryotes are able to grow at higher temperatures than eukaryotes
• Organisms with the highest temperature optima are Archaea
• Nonphototrophic organisms can grow at higher temperatures than phototrophic organisms

Question 5

What hyperthermophile species are present in in hot springs?

Answer 5

• Chemoorganotrophic and chemolithotrophic species present

* High prokaryotic diversity (both Archaea and Bacteria represented)

Question 6

What are microbial mats?

Answer 6

• Thermal gradients form along edges of hot environments

* Distribution of microbial species along the gradient is dictated by organism’s biology

Question 7

High temp challenges? How to overcome?

Answer 7

-Denaturation of proteins, membranes, genetic material
-need thermostability
-Produce thermostable proteins
•critical amino acid substitutions provide more heat- tolerant folds
• increased number of ionic bonds between basic and acidic amino acid – resists unfolding
• production of solutes (e.g., di-inositol phophate, diglycerol phosphate) help stabilize proteins

Question 8

How to overcome high temp challenges?

Answer 8

1. produce chaperonins- a type of HSP that helps other proteins refold and restore following denaturation
   • heat shock proteins - expression is increased when Temp rises
   • HSP found in virtually all organisms
   • intra-cellular
2. increased # of disulfide bridges H bonds in peptides, interactions among aromatic peptides
3. produce DNA gyrase –enzyme that supercoils DNA
4. Modifications to membranes

Question 9

Explain chaperonins. What do they help with?

Answer 9

• Large cylindrical protein complexes that assist the folding of a subset of newly-synthesized proteins in an ATP-dependent manner
• By helping to stabilize partially unfolded proteins, HSPs aid in transporting proteins across membranes within the cell

Question 10

What are some modifications in cytoplasmic membranes to ensure heat stability?

Answer 10

• Bacteria have lipids rich in saturated fatty acids

* Archaea have lipid monolayer rather than bilayer

Question 11

Phospholipids are unusual in what four ways?

Answer 11

1. lipid tails of the phospholipids are chemically different from other organisms
2. bacteria and eukaryotes are mainly glycerol- ester lipids but archaea membranes composed of glycerol-ether lipids
3. archaeal lipids have unique stereochemistry of the glycerol group
4. phospholipid bilayer is replaced by a single monolayer cell wall is similar to gram +’ve bacteria

Question 12

What was the first extremophile? What were TD Brock’s finding? How is its DNA used?

Answer 12

Thermus aquaticus
• T.D. Brock sampled a pink bacteria from Mushroom
Spring, YNP in the 1960’s
• Brock and under- graduate student H. Freeze isolated an organism thriving at 70°C
• Kept looking, and eventually, he found organisms that could live and reproduce near the temperature of boiling water 100 °C
• At least 50 species of thermophilic bacteria which tolerate or require temperatures near water’s boiling point
• it was the first of the Archaea
• thermostable DNA polymerase from Thermus aquaticus is used in PCR reactions

Question 13

Whats a hyperthermophile?

Answer 13

Loves extremely high temperatures (80+°C – upper limit of growth currently 122°C)

Question 14

Whats Geogemma barossii?

Answer 14

• closely related to Pyrodictium and Pyrobaculum

* grows chemoautotrophically using formate as an electron donor and FeIII as an electron acceptor

Question 15

Autoclaves and thermophiles

Answer 15

Some bacteria can withstand autoclaves very high heat

Question 16

What are thermophile enzymes biotechnological applications?

Answer 16

used to convert millions of pounds of corn (maize) into sweetener

Question 17

Whats an acidophile? Alkaliphile? Neutrophile?

Answer 17

Acidophile- organisms that grow best at low pH (<6)
Alkaliphile- organisms that grow best at high pH (>9)
Neutrophile- Grows best between pH 6 and 8

Question 18

Examples of acid env?

Answer 18

Sulphidic pools, geothermal

vents

Question 19

Is the pH of an acidophile cell acidic?

Answer 19

No its neutral or mildly acidic at 6.5

Question 20

Whats acid mine drainage?

Answer 20

• Aphotic environment based on chemolithoautotrophy.
• Mining of pyrite (FeS2) deposits results in S2- oxidized to SO42+ + H+
• Lower pH mobilizes metals
• Acidic effluent with high metal content in which specialized microbial communities develop

Question 21

Explain the 8 steps H+ pump is tied to energy generation.

Answer 21

1. blocking of H+ by cell
   membrane
2. reverse membrane potential through K transport
3. 2nd’ary transporter protein drives transport of nutrients and solutes
4. pump actively
   removes H+
5. vesicles containing H+ avoid acidification of cytoplasm, but still generate ATP from the electrochemical gradient
6. uncharged organic acids (uncouplers) permeate membrane and release H+
7. heterotrophic acidophiles may degrade the uncouplers
8. alternatively, cyto enzymes or chemicals may bind or sequester the protons

Question 22

Whats Sulfolobus acidocaldarius?

Answer 22

• generally spherical cells producing frequent lobes
• facultative autotrophy with growth on sulphur or on a variety of simple organic compounds
• unusual cell wall structure devoid of peptidoglycan
• pH optimum of 2–3 and range from 0.9–5.8;
• with temperature optimum of 70–75°C and range from 55 – 80°C (one strain grew at 85°C)

Question 23

Whats Sulfolobus solfataricus? Where does it grow? What enzyme does it produce? Why does it have strangler proteins?

Answer 23

• grows in terrestrial volcanic hot springs optimally 80°C and pH 3
• grows on a variety of different carbon sources like trypton, various sugars or amino acids
• alcohol dehydrogenase (ADH) that can survive to 88 °C and pH 3.5
• ADH catalyzes the conversion of alcohols and has considerable potential for biotechnology applications due to its stability under these extreme conditions
• protein products from these genes form a sharp band in the middle of the cell, between newly segregated chromosomes, and then gradually constrict the cell such that two new daughter cells are formed

Question 24

What are Sulfolobus sp. cells are covered by? How do they keep an internal pH of 6.5?
What can they oxidize? Where do they grow?

Answer 24

-a hexagonally symmetric surface (S)-layer of glycoproteins
-highly proton impermeable allowing Sulfolobus to keep an
internal pH of 6.5 in an acidic surrounding
some Sulfolobus strains are
-able to oxidize iron in the presence of sulphur, most also grow heterotrophically

Question 25

What algae are good acidophiles? (4)

Answer 25

• the unicellular red alga Cyanidium caldarium
• the green alga Dunaliella acidophila, are both of which
can live below pH 1.
• three fungi, Aconitum cylatium, Cephalosporium sp., and Trichosporon cerebriae, grow near pH 0
• another species, Ferroplasma acidarmanus, has been found growing at pH 0 in acid mine drainage in Iron Mountain in California.