Abstract:Objective In view of the production and environmental issues caused by excessively high nicotine content in upper tobacco leaves, this study aims to decipher the molecular mechanism of nicotine degradation by an efficient nicotine-degrading strain Pu17 screened out in the previous study via genomic approaches.Methods The taxonomic status of the strain was determined by average nucleotide identity (ANI) analysis. Whole genome sequencing and annotation were employed to clarify the nicotine metabolic pathway. Key intermediates during degradation were detected by MS/MS. Live plant trials were conducted to explore the optimal application method for nicotine reduction.Results Phylogenetic analysis revealed an ANI value of 96.51% between Pu17 and Peanarthrobacter ureafaciens, identifying Pu17 as a strain of P. ureafaciens. The genome of Pu17 was 4.47 Mb in length, with the G+C content of 63.34%, encoding 4 155 proteins. Functional annotation and comparative genomics identified unique gene clusters related to heavy metal resistance, cell surface synthesis, and metabolic potential in Pu17, which constituted its environmental adaptation strategy. Metabolite analysis detected key intermediates such as 6-hydroxypseudooxynicotine. This result, combined with that of genomic analysis, confirmed that Pu17 degraded nicotine via the pyridine pathway, with key genes (e.g., nboR, mao, and 6-hlno) primarily located on plasmids. Efficacy evaluation demonstrated that the Pu17 fermentation broth effectively reduced nicotine content in tobacco plants through both foliar spraying and root irrigation, achieving a maximum degradation rate of 14.00% in live leaves.Conclusion This study systematically elucidates the molecular mechanism and application potential of P. ureafaciens Pu17 for nicotine degradation from genomic, metabolomic, and application perspectives. It provides a theoretical basis and microbial resources for the development of bioremediation technologies for tobacco waste and harm reduction.
