Whitaker 3 2-28-11 17 - Chemicals Light Energy for life...

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Unformatted text preview: Chemicals Light Energy for life Phototroph organic (e.g. glucose) inorganic (e.g. ammonia) Chemotroph lithotroph organotroph Phosphate cycle - not a big part of the buffet Phosphorous is cycled mostly in its oxidized state. It can be an electron acceptor for anaerobic respiration resulting in phosphine PH 3 Phosphate is a limiting nutrient because it precipitates with calcium, magnesium and iron ions and is no longer bioavailable. Redox Cycle for Iron SO 4-2 /HSO 3- 2H + /H 2 S /HS- CO 2 /CH 4 Fe +3 /Fe +2 NO 2- /N O NO 3- /NO 2- O 2 /H 2 O Microbial Buffet Electron Tower reduced SO 4-2 /HSO 3--0.52 Fe +3 /Fe +2 +0.77 CO 2 /CH 4-0.24 2H + /H 2-0.41 NO 2- /N O +.036 S /HS--0.27 NO 3- /NO 2- +0.43 O 2 /H 2 O +0.82 E ’ < E ’ oxidized Iron Reducers Geobacter sulfurreducans Eats hydrogen and breathes iron using “nanowires” SO 4-2 /HSO 3--0.52 Fe +3 /Fe +2 +0.77 CO 2 /CH 4-0.24-0.41 NO 2- /NO +.036 S /HS--0.27 NO 3- /NO 2- +0.43 O 2 /H 2 O +0.82 2H + /H 2 Iron Reducers Geobacter sulfurreducans Can also eat other reduced substances such as acetate SO 4-2 /HSO 3--0.52 Fe +3 /Fe +2 +0.77 CO 2 /CH 4-0.24-0.41 NO 2- /NO +.036 S /HS--0.27 NO 3- /NO 2- +0.43 O 2 /H 2 O +0.82 2H + /H 2 CO 2 /acetate--0.29 Which yields more energy acetate or H 2 Iron Reducers SO 4-2 /HSO 3--0.52 Fe +3 /Fe +2 +0.77 CO 2 /CH 4-0.24-0.41 NO 2- /NO +.036 S /HS--0.27 NO 3- /NO 2- +0.43 O 2 /H 2 O +0.82 2H + /H 2 CO 2 /acetate--0.29 In what type of environment would you find iron reducers? Aerobic? Anaerobic? Geobacter sulfurreducans Iron Reducers SO 4-2 /HSO 3--0.52 Fe +3 /Fe +2 +0.77 CO 2 /CH 4-0.24-0.41 NO 2- /NO +.036 S /HS--0.27 NO 3- /NO 2- +0.43 O 2 /H 2 O +0.82 2H + /H 2 CO 2 /acetate--0.29 Energy is generated through electron transport where terminal ferric iron reductase reduces Fe +3 (ferric iron) to Fe +2 (ferrous iron) Geobacter sulfurreducans Nanowires Nanowires transfer electrons to reduce extracellular Fe(III) iron oxides Geobacter Nanowires Fe(III) G. Reguera, et al. Extracellular electron transfer via microbial nanowires. Nature. 435, 7045. Microbial fuel cells Electrons flow from reduced anode to the cathode chamber Geobacter metallireducens Most iron reducers can reduce...
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Whitaker 3 2-28-11 17 - Chemicals Light Energy for life...

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