Carbon monoxide oxidation by chemolithotrophic ammonium oxidizers

Abstract

Chemolithotrophic nitrifying bacteria were examined with respect to their ability to oxidize carbon monoxide in the presence and absence of ammonium. All of the ammonium oxidizers tested, including Nitrosomonas europaea and Nitrosococcus oceanus, were able to oxidize CO to CO₂ in the presence and absence of ammonium. None of the organisms tested incorporated any of the carbon from CO into cellular components in the absence of ammonium. All were able to oxidize CO at trace concentrations of 4 N. The CO oxidation rates at a CO concentration of 300 nL/L in the absence of ammonium ranged from 0.048 nmol/h per 10⁶ cells for Nitrosomonas sp. 4W30 to 0.0025 nmol/h per 10⁶ cells for N. europaea.