초록
Escherichia coli produces molecular hydrogen (H<SUB>2</SUB>) during glucose fermentation. This production of H<SUB>2</SUB> occurs via multiple and reversible membrane-associated hydrogenases (Hyd). Dependence of H<SUB>2</SUB> producing rate (V<SUB>H'2</SUB>) by Hyd-4 (hyf) on glucose concentration was studied at different pHs. During growth on 0.2% glucose at pH 7.5 in JRG3615 (hyfA-B) and JRG3621 (hyfB-R) mutants (V<SUB>H'2</SUB>) was decreased ~6.7 and ~5 fold, respectively, compared to wild type. Only in JRG3621 mutant at pH 6.5 and 5.5 (V<SUB>H'2</SUB>) was severely decreased ~7.8 and ~3.8 fold, respectively. But when cells were grown on 0.8% glucose no difference between wild type and mutants was detected at any of the tested pHs. The results indicate Hyd-4 H<SUB>2</SUB> producing activity inhibition by high concentration of glucose mainly at pH 7.5. This is of significance to regulate Hyd activity and H<SUB>2</SUB> production by E. coli during fermentation.