Microbial Proceses Of Microbial Significance

Question 1

What cycles do microorganisms play an important role in?

Answer 1

Carbon cycle
Nitrogen Cycle
Sulfur cycle
Iron cycle

Question 2

How are microorganisms important in primary production?

Answer 2

-majority of silicate and carvings mineral
deposits are driven by algae primary production (diatoms and calcifying algae)
-organic material derived from photosynthesis drives geochemical processes
-production of fossil fuel reserves

Question 3

How are microorganisms important in production and consumption of atmospheric gases?

Answer 3

-microorganisms contribute substantially to overall atmospheric gas
-most methane produced from microbial activity from Methanogenic Archaea
-nitrous oxide produced by the mostly anaerobic process denitrification by denitrifying bacteria

Question 4

How are microorganisms important in Acid mine drainage?

Answer 4

-Bacterial oxidation of iron sulfied minerals is a major factor in the formation of avid mine drainage. One of the most common forms of iron sulfied is pyrite FeS2

-oxidation of pyrite exposed by mining operations is important in the development of AMD:

     Initiator reaction: 
     2FES2 + 7O2 + 2H2O > 2Fe(2+) + 4SO4(2-) + 4H(+)
    Next reaction: Fe(2+) oxidised to Fe(3+)
    4Fe(2+) +O2 + 4H(+) > 4Fe(3+) + 2H2O
    Next reaction: Fe(3+) undergoes hydrolysis reactions and       precipitates as ferric hydroxide producing more acidity 
    4Fe(3+) + 12H2O > 4Fe(OH)3 + 12H(+)

However once acidic conditions are established, Fe(2+) is chemically stable.

Another reaction in acid mine drainage:

   First reaction: Under acidic conditions Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans rapidly catalyse the oxidation of Fe(2+) to Fe(3+) 
    4Fe(2+) + O2 + 4H(+) > 4Fe (3+) + 2H20
    Next reaction: propagation cycle- Fe(3+) under acid conditions is soluble and rapidly chemically oxidizes more pyrite to form Fe(2+) and sulfuric acid.
     FeS2 + 14Fe(3+) +8H2O > 15Fe(2+) + 2SO4(2-) + 16H(+)

Question 5

How do microorganisms play a significant role in mineral formation?

Answer 5

-Sedimentary carbonates (foraminifera and coccolithophroid algae)
-Sedimentary silicates (diatoms)
-Elemental sulfur (sulfide-oxidising bacteria)
-Sulfide minerals (sulfate reducing bacteria)
-Magnetite- some bacteria are able to precipitate magnetite from the reduction of ferric ion. These organisms precipitate amorphous magnetite. Magnetotactic bacteria precipitate magnetite as magnetosomes. Use these curtains to align themselves in Earths geomagnetic field and thus find out which way us uo in sedimentary and aquatic environments