초록
Rhodobacter sphaeroides MDC 6521 isolated from Arzni mineral springs in Armenia is able to produce bio-hydrogen (H<SUB>2</SUB>) in anaerobic conditions upon illumination in the presence of various metal ions. The significant aspect in regulation of H<SUB>2</SUB> production by these bacteria and its energetics is the requirement for F<SUB>0</SUB>F<SUB>1</SUB>-ATPase, the main membrane enzyme responsible for generation of proton motive force under anaerobic conditions. In order to determine the mediatory role of F<SUB>0</SUB>F<SUB>1</SUB> in H<SUB>2</SUB> production, the effects of various metal ions (Mn<SUP>2+</SUP>, Mg<SUP>2+</SUP>, Fe<SUP>2+</SUP>, Ni<SUP>2+</SUP>, and Mo<SUP>6+</SUP>) on N,N'-dicyclohexylcarbodiimide inhibited ATPase activity of R. sphaeroides membrane vesicles were investigated. These ions in appropriate concentrations considerably enhanced H<SUB>2</SUB> production, which was not observed in the absence of Fe<SUP>2+</SUP>, indicate the requirement for Fe<SUP>2+</SUP>. The R. sphaeroides membrane vesicles demonstrated significant ATPase activity. In the absence of Fe<SUP>2+</SUP> inhibition (~80%) of ATPase activity was observed, which was increased by addition of metal ions. A higher ATPase activity was detected in the presence of Fe<SUP>2+</SUP> (80 μM) and Mo<SUP>6+</SUP> (16 μM). These results indicate a relationship between the F<SUB>0</SUB>F<SUB>1</SUB>-ATPase activity and H<SUB>2</SUB> production that might be a significant pathway to provide novel evidence of a requirement for F<SUB>0</SUB>F<SUB>1</SUB>-ATPase in H<SUB>2</SUB> production by R. sphaeroides.