Results
Significant microbial shifts were observed between OSCC and healthy groups. OSCC samples showed enrichment of taxa, which further identified as conserved taxa such as Porphyromonas, Fusobacterium, Campylobacter, Catonella, Prevotella, Selenomonas, and Veillonella, with species including Campylobacter showae, Capnocytophaga granulosa, Capnocytophaga leadbetteri, Prevotella loescheii, Streptococcus anginosus, Streptococcus pneumoniae, and Treponema medium. Healthy individuals exhibited higher levels of Actinobacillus, Corynebacterium, Escherichia-Shigella, and Haemophilus, particularly H. parainfluenzae, Rothia aeria, R. dentocariosa, and Selenomonas spp. Bray-Curtis beta-diversity analysis confirmed significant compositional differences between groups. Sample type and geography-based comparisons revealed additional variation: Geographically, Lautropia and Haemophilus were common across regions, whereas Cutibacterium, Escherichia-Shigella, Gracilibacteria, and several species appeared specific to India. Functional predictions revealed enrichment of pathways related to environmental and genetic information processing, as well as cellular processes in OSCC. Notably, significant enrichment of genes involved in inflammation, ABC transporters, and bacterial immunity was observed in OSCC groups.