The aim of this project was to evaluate the role of quinone biosynthesis through the targeted disruption of a gene encoding an enzyme essential to the menaquinone biosynthesis in E. faecalis. Compared with its wild-type counterpart, menaquinone biosynthesis mutants displayed an approximate 20% increase in sensitivity to hydrogen peroxide which indicates menaquinone biosynthesis may ultimately play a role in the mediation of oxidative stress in E. faecalis.