Abstract
A mutual symbiotic enhancement of growth of Porphyromonas gingivalis and Treponema denticola is described in this report. Brain heart infusion broth supplemented with vitamin K did not support the individual growth of P. gingivalis or T. denticola. However, when inoculated as a mixture, both bacterial species did grow significantly. The growth-stimulating factors produced by P. gingivalis and T. denticola were dialyzable and heat stable and were further identified as isobutyric acid and succinic acid, respectively. Since some forms of periodontal disease are associated with the presence, in affected sites, of high numbers of P. gingivalis and spirochetes, it is suggested that the bacterial interaction described in this report might be of utmost importance in the initiation and progression of the disease.