Leptothrix species

Bacteria which oxidize ferrous iron (Fe2+) to ferric iron (Fe3+) such as Gallionella and Leptothrix species are termed metal-depositing bacteria. The result of this metabolic process is the formation of ferric hydroxide. 

It should be noted that the kinetic rate law described above is quantitatively applicable only to the strain of L. discophora used in the experiments described. Different Mn-oxidizing bacteria and even different stains of L. discophora would be expected to exhibit different rates of catalysis of Mn oxidation. For example, recent investigations in a wetland in New York State found many different genetic strains of Leptothrix, each exhibiting different rates of catalysis of Mn oxidation (Verity, 2001). However, the general form of the rate law could be expected to be similar for different species of Mn oxidizers. 

Because Mn(II) is stable at pH <8, significant contributions from microorganisms to Mn(II) oxidation has been relatively easy to demonstrate, and a number of Mn(II) oxidizing bacteria have been isolated. Microbial oxidation is considered the primary mechanism of Mn(II) oxidation in circumneutral freshwater (Ghiorse, 1984 Nealson et al., 1988). The sheathed bacterium Leptothrix discophora is perhaps the most-studied species of Mn(II)-oxidizing bacteria, and rate laws have been developed to describe Mn(II) oxidation as a function of pH, temperature, dissolved O2, and Cu concentration (Zhang et al., 2002). Bacillus sp. 

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