Reduced sulfur energy source

Natural gas will continue to be substituted for oil and coal as primary energy source in order to reduce emissions of noxious combustion products particulates (soot), unburned hydrocarbons, dioxins, sulfur and nitrogen oxides (sources of acid rain and snow), and toxic carbon monoxide, as well as carbon dioxide, which is believed to be the chief greenhouse gas responsible for global warming. Policy implemented to curtail carbon emissions based on the perceived threat could dramatically accelerate the switch to natural gas. 

Cork [283], Sublette [284], and others have identified a number of chemolithotrophic bacteria which oxidize elemental sulfur and use reduced or partially reduced sulfur compounds as an energy source, in the presence of various carbon sources (such as carbon dioxide or bicarbonate) and reduced nitrogen (e.g., ammonium ion). In the case of Cork et al. s work, the anaerobic photosynthetic bacterium Chlorobium thiosulfatophilum is used to convert sulfides to sulfate. The economics of this process was not favorable due to the requirement of light for the growth of the bacterium. 

Rhodobacteria (purple non-sulfur) Phototrophic (light user) (use reduced carbon as energy source)... 

Rusticyanin is found in Thiobacillus ferrooxidans, an acidophilic, chemolithotrophic sulfur bacterium utilizing Fe + and reduced sulfur compounds as its sole energy source. T. ferrooxidans does not produce rusticyanin when grown on reduced sulfur. Similar to other substrate-inducible cupredoxms, the msticyanin gene is activated when soluble iron is present in the media. Little is known about its redox partners and it should be noted that rusticyanin itself does not carry out Fe + oxidation. Other iron-oxidizing bacteria, for example, Leptospirillum ferrooxidans, prodnce a cytochrome which substitutes rusticyanin functionally. To date T. ferrooxidans remains the only source for rusticyanin. 

Figure 19, Simplified conceptual representation of the Oparin-Haldane model for origin of life. UV, lighting discharges or other energy sources results in organic matter synthesis from the constituents of a reducing atmosphere. Some photoo.xidation occurs in the upper layers of a primordial ocean with phosphate and sulfur Incorporation and polymerization taking place in lower layers. Evolution leads to a heterotroph initially. Phylogenetic development is unclear (Fenchel et ai. 1998)...

Numerous so-called sulfur bacteria produce sulfur sols which are similar in their chemical and physical properties to the above described Weimarn, Raffo, or Selmi sols. Such bacteria live in all wet environments from soils, ponds, creeks, rivers, and lakes to seashores [49]. The oxidizing sulfur bacteria oxidize reduced sulfur compounds like sulfide ions either by molecular oxygen or, using sunlight as an energy source, by carbon dioxide to the level of S°, i.e., sulfur in the zero oxidation state ... 

Most important in the classification of sulfur bacteria is the distinction between phototrophic and chemotrophic sulfur bacteria. Phototrophic (purple or green) bacteria use light as energy source to reduce CO2 to carbohydrates. Reduced sulfur compounds are used as an electron donor for this reduction, which takes place under anaerobic conditions. The oxidation reactions of sulfide to sulfur and sulfate by phototrophic bacteria are called the Van Niel reactions ... 

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