Abstract
It has been known that, nitrite, one of the precursor of nitrosoamine, is formed by the oral bacteria that reduce nitrate. We have tested the human salivary samples obtained periodically from four healthy adults at about one week interval for the numbers and the populations of aerobic and anaerobic bacteria that could reduce nitrate.
In the samples tested, about 22% of the bacteria isolated were found to reduce nitrate, and 80% of them were anaerobes.
The nitrate-reducing bacteria frequently encountered were Veillonella, Propionibacterium, Corynebacterium, Micrococcus, Neisseria and Lactobacillus.
There was no significant difference in the ability to reduce nitrate among the Veillonella alcalescense Micrococcus sp., Corynebacterium sp., Staphylococcus epidermidis and Staphylococcus aureus, all isolated from the salivary samples. On the other hand, the extent of further reduction of the nitrite was found to differ with these bacterial species, and was also greatly influenced by the cultural conditions.
