The Cyclodextrin Glycosyltransferase ofPaenibacillus pabuliUS132 Strain: Molecular Characterization and Overproduction of the Recombinant Enzyme

[摘要] The gene encoding the cyclodextrin glycosyltransferase (CGTase) ofPaenibacillus pabuliUS132, previously described as efficient antistaling agent and good candidate for cyclodextrins production, was cloned, sequenced, and expressed inEscherichia coli. Sequence analysis showed that the mature enzyme (684 amino acids) was preceded by a signal peptide of 34 residues. The enzyme exhibited the highest identity (94%) to theβ-CGTase ofBacillus circulansno. 8. The production of the recombinant CGTase, as active form, was very low (about 1 U/mL) in shake flasks at37∘C. This production reached 22 U/mL after 22 hours of induction by mainly shifting the postinduction temperature from 37 to19∘Cand using 2TY instead of LB medium. High enzyme production (35 U/mL) was attained after 18 hours of induction in fermentor using the same culture conditions as in shake flask. The recombinant enzyme showedVmax⁡andKmvalues of253±36 μmol ofβ-cyclodextrin/mg/min and0.36±0.18 g/L, respectively.

[学科分类] 基础医学