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- Title
Cloning, expression and enzymatic properties of dextranase from Streptococcus mutans.
- Authors
RU Weijuan; XIA Bingbing; YANG Jingwen; ZHANG Hongbin; HU Xueqin
- Abstract
Dextranase is an anhydroglucose hydrolase widely used in food, medicine, chemical industry and other fields. Dextranase derived from Streptococcus mutans has the characteristics of short fermentation period and high hydrolysis efficiency. In this study, the dextranase (Smdex) gene from Streptococcus mutans was successfully cloned. It was transformed into E. coli BL21 (DE3) to induce the expression of Smdex. This study showed that the optimum temperature of Smdex was 40 °C. At 40 °C, t1/2 was 196 min. The optimum pH of Smdex was 5.5, it could maintain 80% of the enzyme activity at pH 4.5 ~ 10. The Smdex had good thermal stability and pH stability. When dextran T70 was used as substrate, the Km of the enzyme was 3.6 mmol/L and kcat was 140 s-1. Dextran T70 could be degraded to isomalto oligosaccharides with DP of 3 ~ 10, indicating that the enzyme could be used in preparation of isomalto oligosaccharides efficiently. In addition, Smdex was able to inhibit the growth of Escherichia coli and Staphylococcus aureus. MTT assay showed that Smdex had no toxic effect on epithelial cells and T cells. The preliminary results showed that Smdex had the potential as a safe biological preservative, its hydrolyzate could also be used as a functional prebiotic.
- Subjects
MOLECULAR cloning; ESCHERICHIA coli; T cells; OLIGOSACCHARIDES; DEXTRAN; STREPTOCOCCUS mutans; STREPTOCOCCUS thermophilus
- Publication
China Food Additives, 2023, Vol 34, Issue 1, p92
- ISSN
1006-2513
- Publication type
Article
- DOI
10.19804/j.issn1006-2513.2023.01.011