Identification of potential nicotine-degrading oral bacteria in smokeless tobacco users using MALDI-TOF MS and 16S rRNA gene sequencing

Objectives: This study aimed to identify oral bacterial strains with potential nicotine-degrading capability among smokeless tobacco users and to evaluate microbiome alterations associated with tobacco use. Methods: Salivary samples were collected from 30 smokeless tobacco users and 30 matched controls. Samples were cultured on nicotine-enriched selective media. Isolated colonies were identified using MALDI-TOF MS. Parallel microbiome profiling was performed using 16S rRNA gene sequencing targeting the V3–V4 region. Results: Distinct microbial profiles were observed in tobacco users, with higher abundance of Arthrobacter globiformis, Corynebacterium argentoratense, Bacillus altitudinis, and Micrococcus luteus. These species demonstrated growth in nicotine-based media, indicating metabolic potential for nicotine utilization. Metagenomic analysis further revealed dysbiosis-associated genera such as Prevotella, Fusobacterium, and Streptococcus. Conclusions: Oral microbiota of smokeless tobacco users harbor potential nicotine-degrading bacterial strains. Combined culture-based and molecular identification platforms offer promising avenues for developing microbial-based tobacco harm-reduction strategies.