Pilot study on bacterial diversity in saliva samples from two healthy adults using 16S rRNA sequencing

Background: The objective of this pilot study was to preliminarily investigate bacterial diversity and abundance in saliva samples from two healthy adults using 16S rRNA sequencing. Methods: Two healthy adults donated saliva. Genomic DNA extraction, confirmation of bacterial PCR, and quantification of bacterial load by quantitative PCR (qPCR) were performed. 16S rRNA amplicon sequencing targeting the V3–V4 region was performed. In our analyses, alpha and beta diversity assessments, as well as genus-level taxonomic profiling, were conducted. Results: Sample S1 had a higher bacterial load (about 11.1 million gene copies/µL) than S2 (about 4.6 million gene copies/µL by absolute abundance). S1 trended toward higher species richness and evenness as indicated by alpha diversity measures. Compositional differences between samples were shown to be on the moderate side using beta diversity analysis. Varying relative abundances of these dominant genera included Streptococcus, Prevotella, Porphyromonas, Haemophilus, and Neisseria. Conclusion: This preliminary study demonstrates initial insights into oral microbial diversity in healthy individuals, and further investigation is required to validate these findings.