Purification and some properties of sulfur reductase from the iron-oxidizing bacterium Thiobacillus ferrooxidans NASF-1

Kim Yong Ng, Ryoko Sawada, Sayuri Inoue, Kazuo Kamimura, Tsuyoshi Sugio

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7 Citations (Scopus)


Thiobacillus ferrooxidans strain NASF-1 grown aerobically in an Fe2+ (3%)-medium produces hydrogen sulfide (H2S) from elemental sulfur under anaerobic conditions with argon gas at pH 7.5. Sulfur reductase, which catalyzes the reduction of elemental sulfur (S°) with NAD(P)H as an electron donor to produce hydrogen sulfide (H2S) under anaerobic conditions, was purified 69-fold after 35-65% ammonium sulfate precipitation and Q-Sepharose FF, Phenyl-Toyopearl 650 ML, and Blue Sepharose FF column chromatography, with a specific activity of 57.6 U (mg protein)-1. The purified enzyme was quite labile under aerobic conditions, but comparatively stable in the presence of sodium hydrosulfite and under anaerobic conditions, especially under hydrogen gas conditions. The purified enzyme showed both sulfur reductase and hydrogenase activities. Both activities had an optimum pH of 9.0. Sulfur reductase has an apparent molecular weight of 120,000 Da, and is composed of three different subunits (M(r) 54,000 Da (α), 36,000 Da (β), and 35,000 Da (γ)), as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This is the first report on the purification of sulfur reductase from a mesophilic and obligate chemolithotrophic iron-oxidizing bacterium.

Original languageEnglish
Pages (from-to)199-203
Number of pages5
JournalJournal of Bioscience and Bioengineering
Issue number2
Publication statusPublished - 2000


  • Hydrogen sulfide
  • Hydrogenase
  • Moderate mesophilic
  • Sulfur reductase
  • Thiobacillus ferrooxidans

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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