A nicotine-degrading bacterium, strain HF-1, was isolated from tobacco waste-contaminated soil and identified as a member of Pseudomonas sp. based on morphology, physiological tests, Vitek system (GN+), Biolog GN, 16S rDNA sequence and phylogenetic characteristics. The thermal denaturation test indicated that the G+C content of the DNA of HF-1 was 62.7 mol%. The relationship between growth and nicotine degradation of the isolate suggested that strain HF-1 could utilize nicotine as sole source of carbon, nitrogen and energy. Viridescent pigment was observed during nicotine degradation by strain HF-1. The isolate grew optimally at 30 degrees C, initial pH 6.5-7.5 and 1.3 g l(-1) of nicotine concentration in the nicotine inorganic salt medium, which is basically consistent with degradation of nicotine by the isolate. Strain HF-1 could degrade 99.6% of nicotine under the optimized incubation conditions for 25 h monitored by high-performance liquid chromatography. This study demonstrates that Pseudomonas sp. strain HF-1 had strong ability to degrade nicotine, and may be useful for bioremediation of environments contaminated by tobacco waste.