The interaction between Streptococcus and Lactococcus lactis 1370 on the formation of glucan was studied.
1. When the culture supernatant of Streptococcus mutans Ingbritt strain in M17 broth containing 0.5% yeast extract and 5% sucrose (M17YS broth.) was added in the media of beaker, Streptococcus mutans Ingbritt strain and Streptococcus sobrinus B13 produced more artificial plaque compared with culturing in the media added with the culture supernatant of Streptococcus mutans Ingbritt strain in M17 broth containing 0.5% yeast extract W 17Y 17Y broth) (p<0.05), and were replicated more.
2. When the culture supernatant of Streptococcus sobrinus B13 in M17YS broth was added in the media of beaker, Streptococcus sobrinus B13 produced less artificial plaque compared with culturing in the media added with the culture supernatant of Streptococcus mutans Ingbritt strain in M17Y broth (p<0.05).
3. The weight of artificial plaque produced by Streptococcus mutans Ingbritt strain was significantly reduced to 8.0mg in the media added with the culture supernatant of Lactococcus lactis 1370 in M17YS broth compared with 101.6mg in the media only (p<0.05), and that produced by Streptococcus sobrinus B13 was reduc -d in the media added with the culture supernatant of Lactococcus lactis 1370 in M17YS broth (p<0.05).
4. The weight of soluble glucan in 40ml culture supernatant of Streptococcus mutans Ingbritt strain was 0.002g, and that in 10ml culture supematant of Lactococcus lactis 1370 was 0.076g, while that in the culture supernatant of Streptococcus mutans Ingbritt strain being 0.110g in 30 ml M17YS broth added with 10 ml culture supernatant of Lactococcus lactis 1370.
5. The optical density of absorbance at 5,50 nm was 0.379 and 0.209 in the culture of Lactococcus lactis 1370 added with the culture supernatant of Streptococcus mutans Ingbritt strain and Lactococcus lactic 1370 in M17YS broth, whereas being 0.501 in the culture of Lactococcus lactis 1370 in M17YS broth only.
6. The polymer produced by Lactococcus lactis 1370 was glucan on the thin layer chromatography.
7. The glucan produced by Lactococcus lactis 1370 was water-soluble glucan containing a16 linkages as the main linkage on the thin layer chromatography.
These results indicate that the production of water-insoluble glucan by Streptococcus mutans Ingbritt strain was increased by water-insoluble glucan, but. decreased by water-soluble glucan.
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