Thirty bacterial strains were isolated from soil using nicotine as the only carbon source and a high nicotine degradation bacterium strain,named as DBA5,was screened out from them.Based on standard morphologica1,physiological properties and 16S rDNA analysis,DBA5 was identified as Arthrobacter nicotianae.When the medium with 4.0 g/L nicotine,DBA5 could grow well and degrade 93.32% of nicotine in 48 h.When the medium with 5.0 g/L nicotine,it degrade 65.10% of nicotine in 48 h.The growth and nicotine degradation of DBA5 was declined when nicotine concentration was more than 6.0 g/L,and it degraded less than 7.56% of nicotine.DBA5 showed high ability to degrade nicotine.