Abstract
A bacterial strain F-5-2, isolated from soil and identified as Klebsiella pneumoniae, removed NH4+ completely in 24 h of aerobic cultivation in a medium containing 1 mg/ml of NH4NO3. However, 70% of the NO3− originally provided remained. When 100 μM Fe2+ was added to the medium, both NH4+ and NO3− were removed simultaneously and completely from the culture within 6 h of incubation. In addition, the amount of MoO4− in the medium markedly affected the bacterial cell growth and utilization of NH4+ and NO3−. The bacterium could remove 4 mg/ml of NH4NO3 completely in 48 h of aerobic cultivation in a medium containing 100 μM Fe2+ and 0.8 pM MoO42−. The total nitrogen in the culture containing its cells was decreased to 14% of that in the NH4NO3 originally provided. GC-MS analysis demonstrated that N2 was generated from the nitrogen atoms of both NH4+ and NO3−.