FORMATION OF NITRITE AND NITRATE BY ACTINOMYCETES AND FUNGI

Abstract

Nitrite was produced by strains of Mycobacterium, Nocardia, Streptomyces, Micromonospora, and Streptosporangium in media containing ammonium phosphate as the sole N source. The quantity of nitrite formed was small, and the concentration was affected by pH and by the relative levels of carbon and N. Aspergillus flavus produced little nitrite from ammonium but formed in excess of 100 ppm of nitrate-nitrogen. Peroxidase activity and heterotrophic nitrification were reduced in acid conditions, but mycelial development of the fungus was not markedly affected. The inability of A. flavus to form nitrate and nitrite at low pH appears to result from a selective effect of pH upon nitrification rather than being a consequence of the decomposition of nitrogenous intermediates.