Sulfur reducing activity of Desulfuromonas sp. YSD S-3 bacteria under cultivation at different conditions

Abstract

The sulfur reducing activity of sulfur-reducing bacteria Desulfuromonas sp. YSD S-3 for the influence of aeration, pH and temperature was studied. The highest sulfur redu­cing activity was found in culture fluid (48.4 µM H2S / (min×mg of protein), in sedimentary fraction it was 40 times lower, and in the soluble fraction after destruction of cells sulfur reducing activity it was not detected. Probably, the sulfur reductase of Desulfuromonas sp. YSD S-3 is localized in the cytoplasmic membrane and the reduction of sulfur is performed outside the cell. The sulfur reductase of Desulfuromonas sp. YSD S-3 is sensitive to oxygen and is an inducible enzyme. Maximal sulfur reducing activity occurs on the 5–7 day during the stationary phase of growth and reaches 47.4 µM H2S / (min×mg of protein). 30 °C and pH 7.5 are optimal conditions for sulfur reducing acti­vity of Desul­furomonas sp. YSD S-3. Michaelis constant (Km) of sulfur reductase is 0.22±0.01 mM, maximal velocity (Vmax) – 18.2±0.8 µM of H2S / (min×mg).

Keywords

• sulfur-reducing bacteria
• sulfur reducing activity
• sulfur reductase
• hydrogenase
• hydrogen sulfide