Hyperthermophiles, Acidophiles (Extreme environment II) Flashcards
(25 cards)
What colours does each major taxon produce in a hot spring?
Red- Archae Blue- Bacteria Light green- Algae Brown- Fungi Yellow- Protozoa Dark green- plants Animals- Purple
Whats a Thermophile? Examples?
- Organism that likes a temperature of 60 degrees
- Geobacillus
Whats a Acidophile?
Organism that can withstand acidic environments
Studies of thermal habitats have revealed what?
- 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
What hyperthermophile species are present in in hot springs?
- Chemoorganotrophic and chemolithotrophic species present
* High prokaryotic diversity (both Archaea and Bacteria represented)
What are microbial mats?
- Thermal gradients form along edges of hot environments
* Distribution of microbial species along the gradient is dictated by organism’s biology
High temp challenges? How to overcome?
-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
How to overcome high temp challenges?
- 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 - increased # of disulfide bridges H bonds in peptides, interactions among aromatic peptides
- produce DNA gyrase –enzyme that supercoils DNA
- Modifications to membranes
Explain chaperonins. What do they help with?
- 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
What are some modifications in cytoplasmic membranes to ensure heat stability?
- Bacteria have lipids rich in saturated fatty acids
* Archaea have lipid monolayer rather than bilayer
Phospholipids are unusual in what four ways?
- lipid tails of the phospholipids are chemically different from other organisms
- bacteria and eukaryotes are mainly glycerol- ester lipids but archaea membranes composed of glycerol-ether lipids
- archaeal lipids have unique stereochemistry of the glycerol group
- phospholipid bilayer is replaced by a single monolayer cell wall is similar to gram +’ve bacteria
What was the first extremophile? What were TD Brock’s finding? How is its DNA used?
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
Whats a hyperthermophile?
Loves extremely high temperatures (80+°C – upper limit of growth currently 122°C)
Whats Geogemma barossii?
- closely related to Pyrodictium and Pyrobaculum
* grows chemoautotrophically using formate as an electron donor and FeIII as an electron acceptor
Autoclaves and thermophiles
Some bacteria can withstand autoclaves very high heat
What are thermophile enzymes biotechnological applications?
used to convert millions of pounds of corn (maize) into sweetener
Whats an acidophile? Alkaliphile? Neutrophile?
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
Examples of acid env?
Sulphidic pools, geothermal
vents
Is the pH of an acidophile cell acidic?
No its neutral or mildly acidic at 6.5
Whats acid mine drainage?
- 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
Explain the 8 steps H+ pump is tied to energy generation.
- blocking of H+ by cell
membrane - reverse membrane potential through K transport
- 2nd’ary transporter protein drives transport of nutrients and solutes
- pump actively
removes H+ - vesicles containing H+ avoid acidification of cytoplasm, but still generate ATP from the electrochemical gradient
- uncharged organic acids (uncouplers) permeate membrane and release H+
- heterotrophic acidophiles may degrade the uncouplers
- alternatively, cyto enzymes or chemicals may bind or sequester the protons
Whats Sulfolobus acidocaldarius?
- 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)
Whats Sulfolobus solfataricus? Where does it grow? What enzyme does it produce? Why does it have strangler proteins?
- 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
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?
-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
