Phylloquinone is preferable over menadione as a growth factor for Porphyromonas gingivalis.

Objectives: Porphyromonas gingivalis is the etiological agent of chronic periodontitis. Menadione (vitamin K) and phylloquinone (vitamin K) are well-known growth factors for P. gingivalis, while menadione is widely used in growth experiments. Here we attempted to determine the differences in phylloquinone and menadione in P. gingivalis growth experiments, which have not been well studied to date.

Methods: We investigated the effects of menadione and phylloquinone on the growth of two W83 strains and seven ATCC 33277 strains of P. gingivalis.

Results: The ATCC 33277 strains grew well with phylloquinone at 2.9 μM in a complex medium (nutrient medium) and at 29 μM in two minimal media. In contrast, the W83 strains grew well without menadione or phylloquinone in three different culture media. Menadione at 2.9 μM, the conventionally used concentration for culturing P. gingivalis, supported the growth of most ATCC 33277 strains but inhibited the growth of some W83 and ATCC 33277 strains. Furthermore, menadione at 14.5 μM frequently inhibited cell growth, while phylloquinone at 145 μM promoted cell growth.

Conclusions: These results indicate that menadione and phylloquinone act as growth factors for ATCC 33277 but that menadione also can inhibit P. gingivalis growth. Thus, we propose that phylloquinone be used instead of menadione in P. gingivalis growth experiments requiring vitamin K.