Abstract

Eighteen nicotine-degrading bacteria, which could utilize nicotine as the sole carbon and nitrogen sources, were isolated from tobacco plantation soils in Mile, Yunnan Province, China. These bacteria were identified as Arthrobacter sp. (six strains), Ochrobactrum sp. (five strains), Sphingobacterium sp. (three strains), Sinorhizobium sp. (one strain),Alcaligenes sp. (one strain), Pseudoxanthomonas sp. (one strain) and Delftia sp. (one strain) based on their partial 16S rRNA gene sequences. The member of generaPseudoxanthomonas, Sphingobacterium, Sinorhizobium and Delftia were reported to degrade nicotine for the first time. A phylogenetic tree was constructed based on the 16S rRNA gene sequences of different nicotine-degrading bacteria, and these bacteria clustered into three clades (A, B and C). Moreover, the nicotine-degrading abilities of three bacteria were determined, among them, Sinorhizobium sp. 5-28 showed the highest nicotine-degrading ability, 72.5% nicotine in tobacco leaves was degraded after treating for 12 h. Meanwhile, 47.2 and 51.5% nicotine in tobacco leaves were degraded byOchrobactrum sp. 4-40 and Pseudoxanthomonas sp. 5-52 under the same conditions, respectively. In summary, many nicotine-degrading bacteria were identified in tobacco plantation soils, and these bacteria showed potential applications in tobacco production and environmental bioremediation.

Key words: Tobacco leaves, nicotine-degrading bacteria, phylogenetic analysis, bacteria diversity.