不溶性 Dextran 分解酵素産生菌の分布と 1 菌株の産生する酵素の活性

抄録

Distribution of insoluble dextran (ID) degrading bacteria in human dental plaques was investigated on 120 adults of age 20 to 22. The properties of an isolated strain (DC-16) and the activity of the enzyme (IDase) from the strain was also investigated. Results obtained are summarized as follows. 1. IDase producing bacteria were detected in 35 samples (29.2%) out of the 120 samples of dental plaque obtained from adults of age 20 to 22. 2. Thirty three samples (27.5%) had IDase producing bacteria at over 1% of total bacteria in each sample. 3. In the samples having higher caries activity, more IDase producing bacteria were detected than in the samples having lower caries activity. 4. Sixteen strains (61.5%) out of 26 of isolates tested were Gram positive cocci, 8 strains (30.8%) Gram positive rods and 2 strains (7.7%) Gram negative rods. Eleven strains of isolates were streptococci. 5. The optimal pH of the IDase preparation from DC-16 was 6.0 and the optimal temperature 37℃. The enzyme was inactivated by heating at 60℃ for 10min. 6. DC-16 did not degrade soluble dextran (SD), when it was tested using the GAM agar plate containing SD. 7. DC-16 was identified as Lactobacillus brevis.