Methods: 80 healthy adult volunteers were screened for levels of oral odour using Oral Chroma and stratified into groups of males and females with high or low odour, 39 subjects completed the study. Subjects refrained from oral hygiene and consumption of food and drink for 12 hours prior to sampling. Total DNA was extracted from bacterial samples harvested from saliva and 2 tongue sites, on 2 occasions, per subject. PCR amplification was performed until the end of log phase generating amplicons targeting V4-V6 region of the 16S gene and incorporating identification tags and 454-sequencing adapters. The PCR products were purified and pooled to generate a composite sample and analysed using a Roche GSFLX 454-sequencer with Titanium chemistry. The resulting flowgrams were passed through a de-noising and chimera removal pipeline and the resulting sequences clustered to 3% Operational Taxonomic Units (OTU) and analysed using QIIME and novel statistical methods.
Results: Significant differences were observed in genera present between high and low odour subjects for the microbiome of the tongue and saliva (p<0.05). Increased relative abundance of anaerobic bacteria were observed in saliva for high odour subjects (p>0.0001). On the tongue increased relative abundance of Gram negative aerobic bacteria was observed for high odour samples.
Conclusions: The differences in bacterial relative abundances between high and low odour subjects seen in this study may allow functional differences to be inferred and may provide targets for novel interventions.