Preparation of malto-oligosaccharides with specific degree of polymerization by a novel cyclodextrinase from Palaeococcus pacificus

[Display omitted] •A novel recombinant cyclodextrinase designated PpCD was first characterized.•PpCD has strong hydrolysis specificity to cyclodextrins.•The thermostablity of PpCD contributes to the production of maltoheptaose.•The high purity of maltoheptaose was produced by PpCD using β-CD as substrate.•PpCD can be used to produce specific degree of polymerization malto-oligosaccharide. An open reading frame from Palaeococcus pacificus was discovered by genomic analysis. The recombinant PpCD was proved as novel extremely thermal-stable cyclodextrinase with potential on production of malto-oligosaccharides with specific degree of polymerization. This enzyme has extremely high substrate specificity toward cyclodextrins, while the rates of hydrolysis toward macromolecular or linear substrates such as starch, pullulan and amylose were pretty slow. The optimal pH and temperature of PpCD were determined as 6.0 and 95 °C respectively. It was confirmed that PpCD could produce malto-oligosaccharides with a certain degree of polymerization in consistent with that of cyclodextrin substrates. In this study, the preparation of high purity maltoheptaose was achieved and the suitable β-cyclodextrin concentration was about 8–10%. Therefore, PpCD may have a potential application in the production of specific degree of polymerization malto-oligosaccharides.