Analysis of the Human Oral Microbiome of Smokers and Non-Smokers Using PCR-RFLP and Ribotyping

Abstract

Recent advances in the field of microbial and medical ecology emphasize the critical role played by oral bacteria in the delicate dynamic equilibrium of human health and disease, creating the need to define the bacterial communities associated with healthy and non-healthy conditions and to capture shifts in community structure germane to diagnosis. Employing PCR-RFLP of the 16S rDNA gene from metagenomes and plate-wash (cultured) bacteria of oral wash from 10 volunteers, this study evaluated the stability of oral bacteria in healthy subjects and documented community shifts in smokers. Sequence analysis of selected 16S gene amplicons cloned with the Gene Hunter PCR-Trap vector and pCR 4-TOPO cloning kits was conducted to determine the bacteria identity and diversity indices of the two groups. Ribopatterns generated by the restriction enzymes HaeIII and Sau3AI were significantly (p < 0.05) more distinct compared to AluI using the GelCompare II software cluster analysis. A stable core of bacteria DNA fingerprint was detected in all healthy subjects, and remained unchanged over the study period of 3 months. Signature bands (1500 bp with HaeIII ) in smokers and in non-smokers (800 bp and 700 bp with Sau 3 A 1) were evidently suggesting the presence of potential biomarkers of healthy and non-healthy states. There was no significant difference in the DNA fingerprints of cultured and metagenomic extracts. The genera Xanthomonas , Streptococcus and phylum Candidatus occurred in large numbers in both groups, however, a major shift in composition with the dominance of gram-negative bacteria in smokers compared to healthy subjects was quite remarkable. Taxonomic diversity in smokers was quite high, including members of the genera Rothia , Synechococcus , Neisseria , Thiomargarita and Pyrobaculum. These data highlight the presence of a stable core microbiome amidst a wide diversity, identify a distinct smokers’ cluster and open the way for the search for potential biomarkers for specific diseases.