Bacteria arsenic compounds used

Clearly pollution hazards exist when inorganic arsenic compounds are introduced into an environment where anaerobic bacteria are growing. Arsenic impurities in the phosphate used in detergents and for agricultural practices may pose serious problems because of the continuing synthesis of deadly poisonous methylarsenic compounds. 

At the beginning of the twentieth century, arsenic compounds were used to kill spirochete bacteria, which cause the sexually transmitted disease syphilis. After this amphetamine compound was used to treat syphilis in Europe, the disease rate was reduced by more than half. The antibiotic penicillin has replaced arsenic for most medical purposes... 

Methylation of arsenic is an important pollution problem because of the widespread use of arsenic compounds in insecticides and because of the presence of arsenate in the phosphate used in household detergents.421 422 After reduction to arsenite, methylation occurs in two steps (Eq. 16-45). Additional reduction steps result in the formation of dimethylarsine, one of the principal products of action of methanogenic bacteria on arsenate. The methyl transfer is shown as occurring through CH3+, with an accompanying loss of a proton from the substrate. However, a CH3 radical may be transferred with formation of a cobalt(II) corrinoid.423... 

Redox reactions in soils are affected by a number of parameters, including temperature, pH (see Chapter 7), and microbes. Microbes catalyze many redox reactions in soils and use a variety of compounds as electron acceptors or electron donors. For example, aerobic heterotrophic soil bacteria may metabolize readily available organic carbon using NO3, NOj, N20, Mn-oxides, Fe-oxides and compounds such as arsenate (As04 ) and selenate (Se04 ) as electron acceptors. Similarly, microbes may use reduced compounds or ions as electron donors, for example, NH4, Mn2+, Fe2+, arsenite (AsCXj), and selenite (SeO ). 

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