Deamination of Amino Acids by the Human Oral Flora; Its Role in Dental Caries Immunity

Abstract

Human saliva inoculated into beef broth medium incubated for 8 days and passed through a Seitz filter was bactericidal to Lacto-bacillus acidophilus. The inhibitor was ammonia N2. Similar inhibition resulted from adding NH4 salts at pH of 6.8 or above to saliva reproducing the concs. of N2 produced in salivary cultures. These concs. were as low as 0.5 mg. per ml. NH3 protected against dental caries. Caries-immune subjects were found to have enzyme systems capable of converting at least 6 amino acids into ammonia N3.