Analysis of the mouse oral microbiome

Objectives: The mouse model of periodontal disease is frequently employed to examine the role of putative human periodontal pathogens in periodontal bone loss and also to determine the role of the innate and adaptive immune response in protection from disease.  Recently, we showed that the oral commensal microbiota  of the mouse plays an important role in the development of disease in this model: conventionally reared (SPF) mice develop accelerated bone loss when challenged with Porphyromonas gingivalis whereas mice reared under germ free conditions do not despite being colonized by P. gingivalisto the same extent as  SPF animals. Few studies have examined the composition of the mouse oral microbiome. The aim of this investigation was to address this shortcoming in order to more fully understand the development of periodontal bone loss in this model.

Experimental Methods: Initial studies have focused upon the cultivatable mouse oral microbiota . The oral cavity of SPF mice was sampled for 30 s using sterile swabs and serial dilutions of the extracts were plated onto blood agar plates for aerobic and anaerobic growth and CFU determination followed by isolation of the predominant cultivatable organisms and identification by 16S ribosomal RNA sequence analysis.

Results: Members of the following genera were frequently identified as major components of the cultivatable oral microbiota: Streptococcus; Lactobacillus, Staphylococcus; Enterococcus and Propionibacterium. In general the mouse microbiota appeared  less complex than the human oral microbiota. However, there were significant differences in the overall composition in different batches of the same strain of mouse even from the same supplier. Nonetheless, within the same co-caged group of animals, the microbiota was similar and stable over time.

Conclusions: These studies provide the baseline for further analysis of the role of the commensal microbiota in the development of periodontal disease in the mouse model.