Nitrate Reduction in Bacillus licheniformis in the Presence of Ammonium Salt by Shaking Culture

A nitrate-reducing bacterium was isolated from a hot spring and identified as Bacillus licheniformis. This strain was found to accumulate NO2− in the medium even in the presence of NH4+ by shaking culture when FeSO4 was added to the medium. The NO2− accumulation was due to nitrate reductase activity, and the same accumulation was also recognized in some other bacteria. Since the nitrate reduction had no marked effect on the cell growth, it is possible that this nitrate reduction may not be involved in either an assimilatory or a dissimilatory one like those hitherto reported.