Isolation and characterization of thermotolerant bacterium utilizing ammonium and nitrate ions under aerobic conditions

Abstract

A thermotolerant bacterium, identified as Bacillus licheniformis, completely utilized 0.1% (w/v) NH4NO3at 30 and 50°C under aerobic condition. The addition of 0.5 mM Fe2+to the NH4NO3medium markedly promoted the utilization of NH4+and NO3-. At 50°C, of total nitrogen originally provided, 24% was taken up into the cells and 20% remained in the culture supernatant. Residual nitrogen (56%) was probably removed into the atmosphere. The cell extracts contained enzymes involved in denitrification. GC-MS demonstrated that NH415NO3had been converted to15N2O. These results indicate that the strain has denitrification ability under aerobic condition. © 2007 Springer Science+Business Media B.V.