Pathway of oxidation of pyruvic oxime by a heterotrophic nitrifier of the genus Alcaligenes: evidence against hydrolysis to pyruvate and hydroxylamine.

A heterotrophic nitrifier of the genus Alcaligenes, which grows vigorously on pyruvic oxime, was tested by several methods for possible differences or similarities in metabolic performance between pyruvic oxime and its hydrolysis products, pyruvate and hydroxylamine. Major differences were observed between pyruvic oxime and one or both of the other reductants with regard to growth yield, rates of reductant uptake, rates of oxygen uptake, sensitivity of their oxidations to inhibition by thiocyanate, and performance in reductant pulse experiments. Other oximes, some of which are structural analogs of pyruvic oxime and all of which are potential sources of hydroxylamine, were not metabolized by cells or cell-free extract. Collectively the results indicate a pathway of oxidation of pyruvic oxime to nitrite and CO2 that does not involve its initial hydrolysis, but probably involves the oxidation of N and/or C before C-N bond breakage.