Smoking induced Salivary Microbiome Dysbiosis and is correlated with lipid biomarkers
Background: The oral microbiome plays an essential role in maintaining oral homeostasis and health; smoking significantly affects it, leading to microbial dysbiosis. The study aims to investigate alterations in the oral microbiome composition of smokers in the Qatari population and establish a correlation with lipid biomarkers.  Methods: The oral microbiota was profiled from saliva samples of 200 smokers and 100 non-smokers in the Qatari population, and 16s rRNA V3-V4 region were sequenced using the Illumina MiSeq platform. The operational taxonomic units (OTUs) were clustered using QIIME and the statistical analysis was performed by R.  Results: Non-smokers exhibited a more diverse microbiome, with significant alpha and beta diversity differences between the non-smoker and smoker groups. Smokers had a higher abundance of Firmicutes, Bacteroidota, Actinobacteriota, Patescibacteria, and Proteobactria at the phylum level and of Streptococcus, Prevotella, Veillonella, TM7x, and porphyromonas at the genus level. In contrast, non-smokers had more Bacteroidota, Firmicutes, Proteobacteria, Fusobacteriota, and Patescibacteria at the phylum level, and Prevotella, Streptococcus, Veillonella, Porphromonas, and Neisseria at the genus level. Notably, Streptococcus was significantly positively correlated with LDL and negatively correlated with HDL. Additionally, Streptococcus salivarius, within the genus Streptococcus, was substantially more abundant in smokers.  Conclusion: This study highlights the significant influence of smoking on the composition of the oral microbiome by enriching anaerobic microbes and depleting aerobic microbes. Understanding the impact of smoking on altering the oral microbiome composition and its correlation with chemistry tests is essential for developing targeted interventions and strategies to improve oral health and reduce the risk of diseases.