Microbial assimilation of alkyl nitro compounds and formation of nitrite

Abstract

66 representative strains of bacteria, yeasts and fungi were tested for their ability to grow in a semidefined medium containing 0.5% nitroethane as a nitrogen source. About half of them were found capable of growing in the medium. Hansenula beijerinckii, Candida utilis, and Penicillium chrysogenum were most active in assimilating nitroethane. 2-Nitropropane inhibited growth of most of the microorganisms tested in a medium containing 0.2% peptone and 0.2% glycerol. Hansenula mrakii was found to grow rapidly in the nitroethane-peptone medium after a lag phase. Nitrite was accumulated in the culture fluid after the phase of logarithmic multiplication, and increased with increase of the growth, followed by a decline after the maximum growth. The alkyl nitro compounds were oxidatively denitrified to form nitrite by the crude enzyme from Hansenula mrakii. Nitroethane was generally a poor substrate, but was the best inducer to produce the nitro compounds oxidizing enzyme. 2-Nitro-propane and nitroethane were enzymatically oxidized to nitrite, and acetone and acetaldehyde, respectively, which were isolated as 2,4-dinitrophenylhydrazones and identified. Nitrite formed was found to be reduced into ammonia by the intact cells and also the crude enzyme.