1. Hg 0 Hg 2+ CH 3 Hg + (CH 3 ) 2 Hg [CH 3 - ] 2e - lipophilic HgS, Hg + -S-R HS -, - S-R Fish Children Algae Women Infants Fetus Microbial transformations of mercury in the environment

2. Minnamata Bay Anoxic sediment Hg 2+, Hg 0 CH 3 -Hg +, (CH 3 ) 2 Hg Pathology: constricted visual field, impairment of vibration sense, total blindness, ataxia, necrosis of Glia cells

3. “Life is Redox Chemistry” AH 2 + B A + BH 2  G<0 Energy  G= -nF  E,  E= E acceptor - E donor

5. Carbon and electron flow in sulfidogenic environments Complex organic matter Lactate Propionate Higher fatty acids Alcohols Aromatic compounds H 2, CO 2 Acetate Carbohydrates, nucleic acids proteins, lipids H 2 S, CO 2 SO 4 2- 2 1 2 1 = fermentative bacteria, e.g., lactic acid bacteria, clostridia, enteric bacteria, propionibacteria = sulfate-reducing bacteria, e.g., Desulfovibrio spp, Desulfobacterium spp, Desulfobacter spp, Desulfotomaculum spp.

6. Carbon and electron flow in methanogenic environments Complex organic matter Lactate Propionate Higher fatty acids Alcohols Aromatic compounds H 2, CO 2 Acetate Carbohydrates, nucleic acids proteins, lipids CH 4, CO 2 2 1 1 = fermentative bacteria, e.g., lactic acid bacteria, clostridia, enteric bacteria, propionibacteria = proton-reducing, syntrophic bacteria, e.g., Syntrophomonas spp, Syntrophobacter 4 3 2 3 = homoacetogenic bacteria, e.g., Acetobacterium woodii, Clostrodium aceticum 4 = methanogenic archaea, e.g., Methanosarcina spp, Methanobacterium spp., Methanospirillum spp.

7. Carbon and electron flow in sulfidogenic environments Complex organic matter Lactate Propionate Higher fatty acids Alcohols Aromatic compounds H 2, CO 2 Acetate Carbohydrates, nucleic acids proteins, lipids H 2 S, CO 2 SO 4 2- 2 1 2 1 = fermentative bacteria, e.g., lactic acid bacteria, clostridia, enteric bacteria, propionibacteria = sulfate-reducing bacteria, e.g., Desulfovibrio spp, Desulfobacterium spp, Desulfobacter spp, Desulfotomaculum spp.

9. Oxidative carbon monoxide pathway in Sulfate-reducing bacteria

10. Hg 0 Hg 2+ CH 3 Hg + (CH 3 ) 2 Hg [CH 3 - ] 2e - lipophilic HgS, Hg + -S-R HS -, - S-R Fish Children Algae Women Infants Fetus Mercury in the environment