Formation of Nitrogen, Nitrous Oxide, and Nitric Oxide by Extracts of Denitrifying

Studies on the process of nitrite reduction by cell-free extracts of denitrifying bacteria could materially contribute to our knowledge of its mechanism. Such investigations have so far been limited to those of Yamagata (1) with Bacillus pyocyaneus (Pseudomonas aeruginosa) and of Robinson et al. (‘2) with Micrococcus haZodenitri$cans. Neither of these authors has examined the products of the reaction; Yamagata merely determined that nitrite disappeared under the influence of his preparations, while Robinson et al. observed production of a gas, which was assumed to be nitrogen. In the present investigation it has been found that cell-free extracts of two denitrifying bacteria, Pseudomonas stutzeri and a Bacillus subtilis strain, reduce nitrite to a mixture of gaseous products, consisting principally of nitrogen but also containing appreciable quantities of nitrous and nitric oxides. A preliminary account of this work was reported earlier (3).