L23: More Acidophiles Flashcards
NO: Acidthiobaccilus history and main things
formly part of thiobaccilus
they are chemolithoautotrophs they get energy + e-s from oxidation of inorganic compounds
they generate NADH from reverse electron flow
they fix CO2
NO: What are the reactions of acidophilic bacteria in AMD
- Acidithiobacillus thiooxidans:
FeS2 + 7O2 + H2 O ==> (Fe2+) + SO42- + H+ - Acidithiobacillus ferrooxidans:
Fe2+ + O2 + H+ ==> Fe3+ + H2 O
3A. Spontaneous:
S2- + (Fe3+) + H2O ==> Fe2+ + SO42- + H+
note that Fe2+ cycles back to rxn 2
3B. Spontaneous:
(Fe3+) + H2 O ==> Fe(OH)3 + H
NO: How do you prevent AMD
*seal material off with O2, cap mines and cover piles
*cover mines with fill, soil, vegetation
or practice bioremediation
*limestone channels, wells, ponds sand
NO: Discuss failed and successful bioremediation effots
fail:
*adding sulphate reducing bacteria which should convert SO4 to H2S via aneorbic respiration
Success
*mix AMD drainage liquid, sawdust, SRB
=>cellulotucic + fermentation metabolism of sawdust which consumes O2
=>sawdust cellulose is C source for SRB
=>in aneorbic conditions SRB reduce SO4 to H2S and then H2S reduces Fe3+ => Fe2+ => FeS2 which is neutral
NO: What can re oxidation of FeSe be prevented
essentially to prevent the cycle
you must prevent exposure of reduced compounds to O2 (air)
NO: Generally discuss archaea taxonomy
Best known archeal kingdoms are Crenacrhaeota and Euryarchaeota
Thermoacidophiles are in Crena
Extreme halophiles + methanogens in eury, this includes sulfur and sulfate reducers
Describe Thermacidophiles
*extreme thermophiles that grow at low pH and are sulfur dependant
*hot springs, deep sea thermal vents
*can oxides or reduce S containing compounds
Describe suflur reduction and sulfur/suflide oxidation of thermacidophiles
reduction: So => H2S
* by desulfuro, pyro and sulfolob
* anaerobic conditions use S0 as TEA while oxidising organic energy sources
Sulfide/sulfur oxidation: H2S/S0 + 02 => H2SO4
*in aerobic conditions by sulobolos, use S compounds as energy and e- source
Describe extreme halophiles
*part of euryarch
*grow in aerobic conditions but can survive in anaerobic
*energy via chemoorganotrophic aerobic respiration
*odd shapes
*hypersaline habitats were sea water evaporates
==>brine pools, salt flats
*produce red and purple conidtions
What are the salt requirements for extreme halophhiles
*require high salt
minium is 2M optimum is 4.5
*intracellullar salt i shigh because enzymes require it
Describe cytoplamic membrane of halophilic archaea
- has ETC, H+ -ATPases, transporters
- red carotenoids in membrane give characteristic red colour, carotenoid pigments protect the cells from solar radiation
NO: What is the purple membrane of halophiles, conditions
- lipids plus a purple pigment called bacteriorhodopsin (BR), a membrane-spanning protein that is linked to the carotenoid chromophore retinal
- patches of purple membrane form under anaerobic conditions (low O2)
- however, cell growth stops under anaerobic conditions
*only contains BR-retinal (no ETC etc)
What is the function of BR
*light causes BR retinal to pick up H+ from cytoplasm
*reduction of BR retinal leads to deprotoniation, H+ is released back outside the cell
*so its a light driven proton pump
O2 and purple membrane
When no air growth of cells tops, and purple membrane content increases. When aeration increases purple content stops
What does BR lead to
leads to formation of proton gradient (PMF)
*H+ drives ATP synthesis
*H+ re enter via H+ ATPases on regular membrane
*allows cell to maintain cellular function in aneorbic condition
