Characterising healthy Australian oral microbiomes for 'super donor' selection

Among healthy people, we understand very little about the sociodemographic, lifestyle, and dental hygiene behaviours that shape their oral microbiota. This study investigates how sociodemographic, lifestyle and dental hygiene behaviours shape oral microbiota diversity and composition in an Australian population to better inform healthy oral microbiota donors for Oral Microbiota Transplantation (OMT).

The study comprised 93 healthy adults who underwent comprehensive oral examinations and questionnaires to assess their health status. Participants were excluded if they had any active systemic or oral disease. All completed a questionnaire containing information on socio-economic, lifestyle, behavioural, and oral health factors. Supragingival plaque was collected, and 16S ribosomal RNA (rRNA) amplicon sequencing was used to analyse microbial composition. Associations between the core microbiome, alpha- (within-sample), beta-diversity (between-sample) and an individual's co-variates were tested for statistical significance. A redundancy analysis (RDA), multivariate adonis, differential abundance and correlation analysis were performed to characterise which factors drive the variation in the healthy oral microbiome.

Streptococcus and Corynebacterium were the most prevalent and abundant genera among healthy Australians. The alpha and beta diversity were higher among unemployed non-Australian-born students who consumed low carbohydrates, fat, and sugar and had not visited the dentist for over 12 months. Additionally, beta diversity was significantly higher among daily flossers who abstained from fluoride treatment and had high salivary pH, although no single factor explained >4 % of the total variation (R²= 0.042). Alloprevotella, Lachnosporacea, and Parvimonas were significantly abundant among non-Australians who did not visit the dentist within a year. The RDA analysis revealed associations between microbiome composition and factors such as high carbohydrate, sugar, and fat consumption, low fibre intake, and regular dental checks among Australian-born individuals.

These findings indicate that alpha and beta diversity of the oral microbiome varied significantly with sociodemographic, lifestyle, and dietary factors, including non-Australian birthplaces, unemployment, diet, and infrequent dental visits.

These findings underscore the importance of considering diverse sociodemographic, lifestyle, and dietary factors in oral health management. Before microbiome transplantations, clinicians should account for individual characteristics that may be beneficial for shaping and maintaining optimal oral microbiome diversity and health.