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Copper Acetate Manufacturers(WSDTY) Iron is known to be toxic through the Fenton reaction, but this mechanism depends on the presence of O2 and thus cannot account for anaerobic toxicity. Indeed, iron has not traditionally been considered a toxic metal under environmentally relevant anoxic conditions, although there are a few reports of anaerobic iron toxicity in the literature. No mechanism for anaerobic iron toxicity has been established, and the toxicity reported is not a universal trait: a number of bacteria, including dissimilatory iron reducers, such as Shewanella and Geobacter spp., and iron oxidizers, such as Rhodobacter ferrooxidans SW2 and Rhodopseudomonas palustris TIE-1, tolerate millimolar concentrations of Fe(II) with no obvious growth handicap.

Copper toxicity, in contrast, has been much better studied, because copper is a well-documented pollutant. A survey of public testing data showed that copper levels in U.S. groundwater range from undetectable to approximately 1 mM, with most samples in the nanomolar range. Micro- to millimolar concentrations, which represent the high end of the range, are found particularly in industrial and mining waste streams. There are several mechanisms by which copper is toxic. Under oxic conditions, copper, like iron, can react with hydrogen peroxide to form oxygen radicals [H2O2 + Cu(I) → Cu(II) + HO??? + OH?]. Cu(I) also interferes with the iron-sulfur clusters of some proteins in an oxygen-independent process. To combat these toxic effects, bacteria have sophisticated copper homeostasis systems that can include several types of efflux pumps, chaperones, ligands, and oxidases.

Copper toxicity has also been studied in conjunction with other metals. The effects of copper combined with toxic metals such as zinc, cadmium, lead, silver, and nickel have been extensively documented for a range of organisms. In most of these studies, the effects were found to be additive or even antagonistic (combinations were less toxic than single metals), but in some cases, synergistic toxicity was apparent. To our knowledge, all of these studies were performed under oxic conditions.

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