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Streams draining mine tailings are extremely acidic—the effect of Thiobacillus ferrooxidans oxidizing sulfur and iron in pyrite minerals. What kind of bacteria are these?
-2
+4
+6
0
Photoautotrophs (PA) Chemoautotrophs(CA)
CH
Chemoheterotrophs (CH)
PA
The Sulfur cycle has many important effects on Aquatic Ecosystems
-1 pyrites(PA)
EnergyHOFeSOOHOFeS 8445.72 322
4222
Thiobacillus ferrooxidans oxidizes both the iron, Fe(+2) to Fe(+3)and the sulphur in the pyrites, S(-1) to S(+6) using molecular oxygen.
This reaction splits water to produce a great deal of acid.
How do you suggest that mine tailings should be stored?
Hydrothermal vent fauna: a community founded on Thiobacillus a chemoautotrophic bacteria
The pogonophoran tube worms harbour nodules of Thiobacillus inside their body cavities as mutualistic symbionts
Desulfovibrio : Sulfate reducing bacteriacommonly found in anaerobic aquatic environments with high levels of organic material, such as mud in lakes and ponds.•have metal reductases which can precipitate metal sulfides from the water—•bioremediation potentials for toxic radionuclides such as uranium by a reductive bioaccumulation process.
Sulfate reduction can absorb H+ and counteract acid rainThey also contribute to methylation of Mercury
Chemical equation for the oxidation of acetate by sulfate
Cper donated are 4
per accepted are 8
22
4)( (-2)6)( (0)
222
43
-
-
e
S e
COOHSHSOCOOCH
ECOOHSHSOCOOCH 22
243
Where do sulphate reducing bacteria fit in the functional classification?
http://www.esf.edu/efb/schulz/Limnology/Laboratory/PurpleBacteriafromGreenLake.JPG
Purple Photosynthetic sulfur bacteria (eg Thiocapsa)
•use reduced sulfur as an electron donor during photosynthesis. They are capable of oxidizing both sulfide and other reduced sulfur compounds.
Thiocapsa are found most often in fresh water: lakes, sulfur springs, and waste water ponds. Requires anoxic conditions with light present. Under ideal conditions, Thiocapsa can form dense blooms.
gas vacuoles. Why?
Chemical equation for anoxygenic photosynthesis in purple sulfur bacteria
Cper accepted 4
per donated are 2
612612
)0((0)4)( (-2)
2612622
-
-
e
S e
OHOHCSCOSH
OCHSenergylightCOSH 222
In aerobic photosynthesis O2 is produced. Why is no O2 produced here?
0 V
+0.25
-0.25
Earth’s crust, a reducing environment
Atmosphere, oxidizing environment
Soil layer
Redox profile at the earth’s surfaceThe earth is a 0.5 V battery
Photosynthesis--a strong photochemical redox reaction-- has produced a strong redox gradient across the earth’s surface.
This gradient helps maintain chemical diversity at the boundary Consider the example of soil N