Development of system to recover heavy metal from ore, polluted soil and wastewater by using iron-oxidizing bacterium

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Iron-oxidizing bacterium, Acidithiobacillus ferrooxidans, is one of the most important bacteria for the bioleaching of copper and gold ores. In order to use the mercury reducing activity of A. ferrooxidans for the bioremediation of mercury, mercury-resistant A. ferrooxidans strains SUG 2-2 and MON-1 were screened among 150 strains of iron-oxidizing bacteria isolated from natural environments. It was found that strains SUG 2-2 and MON-1 have a novel ferrous iron-dependent mercury volatilization activity as well as an NADPH-dependent mercury reductase activity. Strain MON-I has volatilization activity an organomercurial lyase-like activity by cytochrome c oxidase. Nearly 100% of the total mercury in mercury-polluted soil or mercury wastewater was volatilized and recovered by incubating SUG 2-2 or MON-1 cells. suggesting that these mercury-resistant strains can be used for the bioremediation of inorganic and organic mercurial compounds.A. ferrooxidans strain D3-2, which has a high copper bioleaching activity, was isolated from a low-grade sulfide are dump in Chile. Since sulfite ion is a highly toxic intermediate produced during sulfur oxidation that strongly inhibits iron oxidase activity, these results confirm hat strain D3-2, with a unique sulfite resistant-sulfite oxidase, was able to solubilize more copper from chalcopyrite than strain ATCC 23270, with a sulfite-sensitive sulfite oxidase. An electric cultivation device was developed. This was useful for the enzymatic refinement and the Applied technology.