Physiologie der Nitratreduktion bei Pseudomonas aeruginosa

By both Pseudomonas strains the N2 and N2O production depended on the “physiological condition” of the bacteria. The N2O formation by strain C 31 in mineral media depended also on the precultivation medium. The bacteria produced N2O besides N2, if precultivated in Nutrient Broth + KNO3. Precultivated in a mineral medium, however, they produced only N2. The anaerobic gas production of Pseudomonas aeruginosa strain C 31 and strain N.C.I.B 8704 was determined under hydrogen atmosphere. The results are as follows: In Nutrient Broth + 0.35% KNO3 nitrate was respirated quantitatively to N2 and N2O by the two strains. On the contrary, in Nutrient Broth + 0.5% KNO3 nitrate was not completely consumed by strain C 31. In nitrate-ammonium-medium we succeeded to recover quantitatively the given nitrogen compounds (nitrate, nitrite, ammonium, organic N), partially in the denitrification products, after the end of the experiment, but not in the experiment with nitrate-medium. In nitrate-medium strain C 31 produced a much higher amount of nitrite (up to 73 mg N/l) as in nitrate-ammonium-medium (up to 213 μg N/l). The influence of the ammonium ions is discussed.