Abstract
An attempt was made to search for the enzymes that degrade insoluble glucans (IG) produced by Streptococcus mutans strain JC2. By screening many soil microorganisms and a veriety of fungi strains, it was found that Streptomyces nigrifaciens ISP 5071 produces these enzymes.
Culture conditions for the enzyme production were tested with the Streptomyces. The enzyme was produced only in the culture containing IG as an inducer. A maximum production of the enzymes was obtained in the culture supernatant when the spore was inoculated in the basic medium containing 0.3% IG, 0.4% glycerol and cultured at 27°C for 4 days under rotary shake of 160 per min.
The crude enzyme solution was prepared from the culture supernatant by precipitation on 30-50% saturation of ammonium sulfate. The degradation activity of the crude enzyme solution toward some glucans was studied.
The results were as follows.
1) The crude enzyme solution readily degraded IG and a modified-IG which consisted only of α-(1→3) glucosidic bond.
2) The crude enzyme solution split IG synergistically in combination with dextranase.
3) Paper chromatographic analysis of the enzymatic digests from IG and modified-IG showed that nigerose was the main reaction product, and that practically no isomaltose and its oligosaccharides were present.
4) The activity of dextranase was not detected in the crude enzyme solution. These results strongly suggested that the crude enzyme solution contains a certain α-(1→3) glucanohy drolase and not α(1→6) glucanohydrolase.
