A new denitrifying bacterium strain ASM-2-3 was isolated from the Ariake Sea tideland, Japan. The isolate had the capability to fully remove as high as 225.8 mg nitrate-nitrogen (.) l(-1) under stationary culture conditions without accumulation of nitrite as an intermediate. From biochemical tests and 16S rDNA sequencing analysis, the genus of the bacterium was identified as Pseudomonas and close to stutzeri species. The nitrate removal efficiency of the isolate was faster than that of the control strain Pseudomonas stutzeri NBRC 14165, using succinate as the sole carbon source. The isolate could grow in up to 10% (w/v) of NaCl containing medium. The enzymatic tests showed that the activity of enzymes responsible for the reduction of nitrate and nitrite in strain ASM-2-3 was 1.4 and 2.3 times higher than that of the control strain. The feasibility of application of the isolate strain ASM-2-3 in a packed bed bioreactor was investigated for 40 d.