Sulfur compound oxidizing bacteri

Oxidation The chemical addition of oxygen to break down pollutants or organic waste (e.g., destruction of chemicals such as cyanides, phenols, and organic sulfur compounds in sewage by bacterial and chemical means). 

OEHHA Office of Environmental Health Hazard Assessment OSHA Occnpational Safety and Health Administration Osteogenic sarcoma Cancer associated with bone structures Oxidation Chemical addition of oxygen to break down pollutants or organic waste, for example, destruction of chemical substances such as cyanides, phenols, and organic sulfur compounds in sewage by bacterial and chemical means Oxidative stress Process whereby the metabolic balance of a cell is disrupted by exposure to environmental substances, resulting in accumulation of free radicals, which can damage the cell... 

Corrosion of concrete by bacteria that oxidize sulfur compounds into sulfuric acid was reported by Parker (1945, 1947) and has been examined more recently by Fjerdingstad (1969). The lowest pH is tolerated by Thiobacillus concretivorus Parker (pH 2.75 + 0.42) and T. thiooxidans Waksman and Joffe (pH 2.35 0.32). Within 100 days of incubation in a T. thiooxidans culture, 60% of a 3.6 g block of concrete were dissolved. Bacterial destructive activity has also been established on buildings and monuments (Krum-... 

The investigations of Landesman et al. (1966a, b) clarify the effects of the various conditions controlling the optimum oxidation rates of ferrous iron, sulfur and reduced sulfur compounds by T. ferrooxidans. Experiments on soluble iron, sulfur and iron-containing sulfide minerals (chalcopyrite, CuFeS2, bornite, CUsFeS4, and pyrite) established that iron and sulfur can be oxidized simultaneously. With a mixed iron-sulfur substrate a rate of oxidation, equal to that of the sum of the maximum rates of oxidation of the two substrates individually was observed with both S-adapted and Fe-adapted cells. Subsequently, Duncan et al. (1967) established the differential susceptibility of the bacterial oxidation of ferrous iron and sulfur to N-ethyl maleimide and sodium azide, and determined the effect of these inhibitors on pyrite and chalcopyrite oxidation. Decreased rates... 

The oxidation of sulfur compounds in the sulfur-oxidizing bacteria is performed by the combination of several elemental reaction processes, and each of the processes is performed by a cooperation of several enzymes and cytochromes. The elemental reaction processes included in the bacterial oxidation of sulfur compounds will be described in the following section. 

In the corroded concrete, there also reside acidophilic iron-oxidizing bacteria (see below) besides the usual sulfur-oxidizing bacteria. The acidophilic iron-oxidizing bacteria show optimal growth pH at 2.0, and oxidize not only ferrous iron but also sulfur compounds. Therefore, they can participate in the corrosion of concrete. We have to consider the action of both the usual sulfur-oxidizing bacteria and the acidophilic iron-oxidizing bacteria when we exploit the compounds which inhibit the bacterial corrosion of concrete. 

When we think of the bacterial-environmental interactions in corrosion on buried steel and cast iron pipes, we have in mind the different reductions and oxidations of inorganic sulfur compounds performed by living bacteria of the sulfur cycle. 

A major contribution of this paper was pointing out the importance of bioturbation and bioirrigation on chemical processes associated with carbonate dissolution. In the movement of sulfidic sediment from depth to near the interface by biological processes, oxidation of the sediment produces sulfuric acid which ends up titrating alkalinity, lowering pH, and thus lowers saturation state (e.g., Berner and Westrich, 1985). Actually this process is very complex, involving many reactive intermediate compounds such as sulfite, thiosulfate, polythionates, etc. Aller and Rude (1988) demonstrated an additional complication to this process. Mn oxides may oxidize iron sulfides by a bacterial pathway that causes the saturation state of the solution to rise with respect to carbonate minerals, rather than decrease as is the case when oxidation takes place with oxygen. 

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