Date of Award


Document Type

Campus Access Thesis


Biological Sciences

First Advisor

Austin L Hughes


This phylogenetic study was undertaken in order to provide further elucidation to evolutionary relationships within the genus streptococcus. The inhibition by Streptococcus oligofermentans of Streptococcus mutans is of particular interest. A comprehensive mechanism for this inhibition has been previously resolved in vitro and isolated to L-amino acid oxidase (LAAO) within S. oligofermentans which produces high levels of H2O2 through the metabolism of seven L-amino. Phylogenetic analysis of coded amino acid (AA) sequences within 20 enterococci present insights into possible methods for control of the etologic factors of dental caries. Analysis of 10 amino acid sequences from 19 Streptococcus species and Lactococcus lactis using pairwise between-species distances and phylogenies based on maximum likelihood (ML) suggest possible horizontal gene transfer (HGT) of L-amino oxidase (lox) conferring inhibitory properties against S. mutans to S. oligofermentans.