Enhancement of cyclodextrin production through use of debranching enzymes

In the presence of a complexant and a debranching enzyme capable of cleaving alpha-(1-->6) linkages in alpha-D-glucans, Bacillus mascerans cyclodextrin glucanotransferase (CGTase; EC 2.4.1.19) converted starch, maltodextrin and glycogen into cyclodextrin (CD) in yields higher than those obtainable in the absence of debranching enzyme. The extent of yield enhancement by pullulanase (EC 3.2.1.41; from Enterobacter aerogenes) was dependent upon temperature, type of substrate (including source of starch) and kind of complexant. Highest yields with pullulanase were attained generally by use of low temperature (15-25 degrees C) and starches of low amylose content. At 25 degrees C and pH 7, with cyclodecanone as complexant, 91-93% yields of beta-CD were obtainable from amylopectin, waxy-maize starch, and tapioca starch. With decan-I-ol as complexant, amylopectin was converted at 15 degrees C into alpha-CD in 84% yield. With cyclotridecanone as complexant, amylopectin was converted at 40 degrees C into gamma-CD in 72% yield. The debranching enzyme isoamylase (EC 3.2.1.68; from Pseudomonas amyloderamosa) was also employed successfully to achieve high beta-CD yields. A 90% yield of beta-CD from amylopectin was obtained by applying isoamylase, CGTase and cyclodecanone at pH 6 and 25 degrees C.