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• EXPRESSION OF CHITINASE GENE FROM Bacillus Licheniformis DSM13 IN E.Coli T7 AND BIOCHEMICAL CHARACTERIZATION OF RECOMBINANT ENZYME

  Nguyen Hoang Anh

  Ngày nhận bài: 26-07-2017 / Ngày duyệt đăng: 05-09-2017 / Ngày xuất bản: 06-08-2025

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  In this study, the mature gene encoding for the enzyme endochitinase from the Gram positive bacterium Bacillus licheniformis DSM13 (ATCC 14580) was cloned into the expression vector pET-21d, and then overexpressed in E. coli T7. A high expression level was indicated by SDS-PAGE and an enzyme activity assay using pNP-(GlcNAc)2 0.18 mM as the substrate. The activity of the enzyme expressed in E. coli T7 was approximately 8 times higher than that previously expressed in Lactobacillus plantarum. Recombinant chitinase was purified from cell extract and characterized using coloidal chitin 2% as the substrate. The enzyme showed good thermostability (half-lives of 15 days and 8 days at 37 and 50° C, respectively), and good stability in the pH range of 5 - 9. The main product of colloidal chitin hydrolysis as indicated by thin layer chromatography was diacetyl glucosamine. The results demonstrated that this enzyme was promising for chitin waste bioconversion into different chitin-oligosaccharides, such as functional diacetyl glucosamine.

  DOI: https://doi.org/10.31817/tckhnnvn.2017.15.9.

• ISOLATION AND CHARACTERIZATION OF THE PHYTASE GENE PROMOTER FROM Bacillus licheniformis DSM13

  Nguyen Thanh Trung, Nguyen Minh Trung, Nguyen Huy Thuan, Trinh Thanh Trung, Nguyen Quoc Trung, Trinh Thi Thu Thuy, Nguyen Hoang Anh

  Ngày nhận bài: 20-09-2017 / Ngày duyệt đăng: 25-03-2017 / Ngày xuất bản: 06-08-2025

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  Phytases are a group of enzymes that hydrolyze phytate to release inorganic phosphate and myo-inositol phosphate intermediates. The phytase encoding gene (phyL) of Bacillus licheniformis DSM13 is strongly induced during phosphate starvation conditions. In this study, we analyzed the activity of the phytase promoter by constructing a recombinant strain containing a plasmid bearing the phyL promoter fragment and the reporter gene xynA (encoding the xylanase) fusion. The recombinant strain was grown in conditions without and with the addition of different concentrations of sodium phytate. The results showed that the phytase promoter was strongly induced when less than 5 mM of phytate was added to the growth medium. Furthermore, growth analysis experiments revealed that phytate was an important alternative phosphate source for B. licheniformis cells to overcome phosphate starvation conditions.

  DOI: https://doi.org/10.31817/tckhnnvn.2017.15.3.