Short Communications Revisiting the role of the electron transport chain in molybdate reduction by Enterobacter cloacae strain 48

Molybdenum reduction to molybdenum blue by microbes is a potential bioremediation tool for molybdenum pollution. A previous work using cyanide as a respiratory inhibitor has shown that the site of molybdenum reduction in Enterobacter cloacae strain 48 is at the electron transport pathway. In the present work, several respiratory inhibitors together with cyanide were used to reinvestigate the site of molybdenum reduction in E. cloacae strain 48. All the respiratory inhibitors tested showed no inhibition to the molybdenum-reducing capability of the bacterium. It was also discovered that cyanide caused a large increase in the pH of the enzymatic reaction mixture and, therefore, the inhibition previously seen was likely due to unfavourable pH for the enzyme activity. Based on these results, the site of molybdenum reduction in this bacterium is suggested not to be the component of electron transport pathway.