Growth of Oral Microflora on Saliva from Different Glands

In this study we have investigated the growth of batch-wise enrichment cultures of supragingival plaque on parotid, (PAR) submandibular-sublingual (SM-SL) and clarified whole (CHW) saliva from one volunteer, who also donated the plaque sample. All three salivas supported rapid growth of a mixed oral microflora. Salivary glycoproteins were completely deglycosylated during growth, while most proteins were left intact. The enrichment cultures on PAR and SM-SL salivas had different microbial compositions. B. oralis was dominant in the culture on PAR saliva, but absent in the culture on SM-SL saliva. In contrast E. lentum was found in a high proportion in SM-SL saliva, but was absent in the culture on PAR saliva. S. mitis was a dominant organism in both cultures, but the isolates from PAR and SM-SL saliva belonged to different biotypes. The enrichment on CHW saliva appeared to have an intermediate composition and most species and biotypes isolated either from the culture on PAR or from SM-SL saliva were found in CHW saliva. The various glycosidase and peptidase activities produced in the enrichment were largely cell-associated and found to be the same as those normally found in saliva and dental plaque in vivo. Taken together the results support the contention that the normal oral microflora maintains itself in the oral cavity by using salivary glycoproteins as a substrate. Moreover saliva seems to act as a selective force in the oral cavity, since different types of glycoproteins as found in PAR and SM-SL saliva supported the growth of different microfloras.