2.4. Bacterial strain and culture conditions
The growth media employed were: brain heart infusion broth
(BHI) for Streptococcus mutans (ATCC 10449) and trypticase
soy broth-yeast extract medium supplemented with cysteine
hydrochloride (0.05%), menadione (0.02 g/mL), hemin (5 g/mL),
and potassium nitrate (0.02%) for Porphyromonas gingivalis ATCC
(33277). Streptococcus mutans strain was incubated at 37
◦
C under
aerobic conditions and Porphyromonas gingivalis anaerobically in
GasPak jars (DB, NJ, USA)