Production of putrescine by salivary microorganism

Abstract

The acids produced in the oral cavity are well known to be responsible for dental caries. Thebases produced therein neutralize these acids and make the surroundings in habitable for oral microorganisms. It is important to investigate the relation between the base production by oral microorganismsand oral diseases.
This investigation deals with the production of putrescine from several precursors by salivary microorganisms. Whole saliva was collected from 9 persons. Three kinds of mixed saliva containingthe same volume of salivas collected from three persons were incubated at 37°C for 48 hours underaerobic (unshaken) condition with deionized water or 25m M precursors (ornithine, arginine, citrulline, agmatine and glutamic acid). Putrescine produced and agmatine remained were determined by isotachophoresis.
Putrescine was produced from saliva containing ornithine, arginine or citrulline but was notdetected isotachop horetically in saliva containing deionized water, agmatine or glutamic acid during 48 hours of incubation. The largest amount of putrescine was produced from ornithine. The amountof putrescine produced from arginine was less than a half of the putrescine produced from ornithineand that from citrulline was quite smaller than the putrescine produced fromarginine. It was confirmedthat agmatine was not produced from arginine in saliva and the agmatineadded in saliva was notdecomposed during 48 hours of incubation. It has been considered that putrescine is produced from argininevia the arginine dihydrolase pathway followed by ornithine decarboxylation by oral microorganisms. However, it was suggested from our experiment that salivary microorganisms produced putrescine fromarginine by the pathway comprising arginase and ornithine decarboxylaseother than via the argininedihydrolase pathway.
pH of saliva containing putrescine-producing amino acids increased with incubation but the pH was not in parallel with the amount of putrescine. The rise of pH was the highest in saliva incubated with arginine and it was due to the volatile base (ammonia) produced with putrescine.