A dextranase preparation obtained from culture of a strain of Spicaria species has been found effective in removing or preventing formation of dental plaque in human in the previous report.
The aim of this study was to clarlify the in vitro effects of this dextranase on different polysaccharides produced by various strains of streptococci
The results were as follows:
1) Polysaccharides were prepared from cultures of 7 strains of cariogenic Streptococcus mutans (strains AHT, Ingbritt, HSR-6, SLR-4, FA-1 and GS-5), a strain of Strept. salivarius (HHT) and a non-cariogenic strain of Streptococcus sp. (CHT). Water soluble polysacharides were obtained from all strains except HSR-6, and insoluble one was from HSR-6. In addition to these polysaccharides KOH soluble one was seperated from strain SLR-4.
2) The analytical data showed that the polysaccharide from strain HHT was of levan type and the others were of dextran type.
3) The effects of each dextranase from Spicaria sp. and Penicillium sp. on various streptococcal polysacharides at pH 5.8 were estimated by calculating the release of reducing groups. Water soluble polysaccharides produced by strains AHT and HHT, and KOH soluble one from strain SLR-4 were not hydrolysed by both dextranases. A dextranase from Spicaria sp. showed strong hydrolysing activity against a soluble polysaccharide of strain FA-1 and an insoluble one of HSR-6, but that from Penicillium sp. did only weak activity upon them. Both dextranases exerted their activities in the similar manner on all the polysaccharides except those described above.
4) At pH 7.0 all streptococcal polysaccharides resisted exclusively hydrolysis with the dextranase from Penicillium sp. But the hydrolysing capacity of the dextranase from Spicaria sp. decreased only slightly.
