Reduction of Hg2+ with reduced mammalian cytochrome c by cytochrome c oxidase purified from a mercury-resistant Acidithiobacillus ferrooxidans strain, MON-1

Tsuyoshi Sugio, Mitsuko Fujii, Yumika Ninomiya, Tadayoshi Kanao, Atsunori Negishi, Fumiaki Takeuchi

Research output: Contribution to journalArticle

7 Citations (Scopus)


Acidithiobacillus ferrooxidans AP19-3, ATCC 23270, and MON-1 are mercury-sensitive, moderately mercury-resistant, and highly mercury-resistant strains respectively. It is known that 2,3,5,6-tetramethyl-p-phenylendiamine (TMPD) and reduced cytochrome c are used as electron donors specific for cytochrome c oxidase. Resting cells of strain MON-1 had TMPD oxidase activity and volatilized metal mercury with TMPD as an electron donor. Cytochrome c oxidase purified from strain MON-1 reduced mercuric ions to metalic mercury with reduced mammalian cytochrome c as well as TMPD. These mercury volatilization activities with reduced cytochrome c and TMPD were completely inhibited by 1mM NaCN. These results indicate that cytochrome c oxidase is involved in mercury reduction in A. ferrooxidans cells. The cytochrome c oxidase activities of strains AP19-3 and ATCC 23270 were completely inhibited by 1μM and 5μM of mercuric chloride respectively. In contrast, the activity of strain MON-1 was inhibited 33% by 5μM, and 70% by 10μM of mercuric chloride, suggesting that the levels of mercury resistance in A. ferrooxidans strains correspond well with the levels of mercury resistance of cytochrome c oxidase.

Original languageEnglish
Pages (from-to)1756-1763
Number of pages8
JournalBioscience, Biotechnology and Biochemistry
Issue number7
Publication statusPublished - 2008



  • Acidithiobacillus ferrooxidans
  • Cytochrome c oxidase
  • Iron oxidase
  • Mercury reduction
  • Mercury resistance

ASJC Scopus subject areas

  • Bioengineering
  • Biotechnology
  • Biochemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Chemistry (miscellaneous)
  • Applied Microbiology and Biotechnology
  • Food Science
  • Medicine(all)

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