Graduation Year


Document Type




Degree Granting Department


Major Professor

My Lien Dao, Ph.D.

Committee Member

Daniel Lim, Ph.D.

Committee Member

Kristina Schmidt, Ph.D.


RNA isolation, Hybridization, Procedure development, Gene expression, Bacterial interaction


The oral pathogen Streptococcus mutans is a known etiological agent for dental root decay and coronal caries. It has been hypothesized, but not yet proven, that S. mutans expression of virulence genes in dental plaque may be influenced by its interaction with co-aggregating partners, notably Fusobacterium nucleatum and Actinomyces viscosus. Investigation of the suitability of mixed cultures of S. mutans with F. nucleatum versus S. mutans with A. viscosus proved that A. viscosus was a better target in the present laboratory setting. Furthermore, A. viscosus, a causative agent of mandible osteomyelitis and endocarditis, has been shown to have direct interaction ability with S. mutans. DNA microarray analysis was used in the present study to investigate the influence of co-aggregation with A. viscosus on the expression of S. mutans genes. Microarrays have been used successfully in the analysis of differential gene expression in S. mutans as a function of culture conditions, such as in biofilms versus planktonic states. This technology however, has not yet been applied to the analysis of homologous versus heterologous cultures. The present study was conducted in order to identify potential problems associated with the application of microarray analysis to mixed cultures. The data obtained encourage the further testing of microarrays for the analysis of heterologous cultures of oral bacteria.