KWRRI Research Reports


Cytochrome transport particles from Nitrobacter catalyzed nitrite, ascorbate as well as NADH oxidation with concomitant phosphate esterification yielding P/0 ratios of 1.0, 0.6 and 2.0 respectively. Phosphorylation coupled to nitrite oxidation was not effected by rotenone, amytal or antimycin while 50 and 70% inhibition of the NADH-linked phosphorylation was observed in the presence of HOQNO and rotenone respectively. Cell-free extracts from Nitrobacter also catalyzed an energy-dependent reduction of NAD+ by nitrite. The reduction of cytochrome c by NŌ2 was energy-dependent which involved the reversal of electrons from cytochrome a1. The subsequent energy-linked reduction of the flavoproteins and pyridine nucleotides occurred concomitantly with the oxidation of cytochrome c. The process of energy-linked reversal of electron transfer in Nitrobacter was markedly sensitive to all the inhibitors and uncouplers.

The reduction of NAD+ by thiosulfate in T. neapolitanus was an energy-linked process and involved the reversal of electrons from ferrocytochrome c mediated by flavoproteins. Cell-free extracts also catalyzed the reduction of NAD+ by sultie at the expense of ATP and involved the participation of the flavoprotein-pyridine nucleotide segment of the respiratory chain. The NADH oxidation by T. neapolitanus was mediated by the flavoprotein and cytochrome systems and this process also appeared to be coupled with energy-generation.

The energy-dependent metabolism of sulfate producing bacteria and nitrite oxidizing bacteria was found to be very markedly sensitive to extremely low quantities of chloro, bromo or nitre-substituted phenols. Investigations which were conducted to assess the importance of these organisms in natural environments seem to be rather important in designing control measures for the control of biological production of sulfur or nitrogen compounds or acidity in acid-mine streams or spoil bank.

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The work upon which this report is based was supported by funds provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Research Act of 1964.