Action of sulfate reducing bacteria

Describe the action of sulfate reducing bacteria around deep wrecks

  • Seawater contains approximately 840 ppm of sulfates.
  • Much corrosion of metals in deep water is caused by anaerobic bacteria that reduce sulfate to sulfide:
                            SO42- + 5H2O + 8e- → HS- + 9OH-
  • This reduction half-equation is accompanied by the oxidation half-equation of the metal involved, such as iron:
                            Fe → Fe2+ + 2e-
  • Combining the above two equations:
                            4Fe + SO42- + 5H2O → 4Fe2+ + HS- + 9OH-
  • The products react to form the insoluble compounds of iron sulfide and iron hydroxide:
                            4Fe2+ + HS- + 7OH- → FeS(s) +3Fe(OH)2(s) + H2O(l)
  • The main sulfate-reducing bacterium is Sporovibrio desulfuricans, which obtains energy from the reduction process.