Characterization of a novel nicotine-degrading Ensifer sp strain N7 isolated from tobacco rhizosphere

An aerobic bacterial strain N7 capable of effectively degrading nicotine was isolated from the rhizosphere of tobacco in Yunnan, China. This strain was identified as Ensifer sp. based on morphology, physiological characteristics, and 16S rDNA sequence analysis. The optimum nicotine concentration for the growth of strain N7 was 2.0 g/l. There was no more nicotine detected in the medium containing 2.0 g nicotine/l after N7 growth for 24 h and less than 16.3% of the nicotine in a medium containing 4.0 g nicotine/l after N7 growth for 48 h. There was a statistically significant linear relationship between nicotine degradation and biomass of strain N7. When a N7 cell suspension (10(8) CFU/ml) was applied to tobacco leaves, the nicotine concentration was decreased by 16.0%. These data suggest that the novel strain N7 of Ensifer may be useful for nicotine biodegradation.