Studies on the Development of Starch-Related Functional Oligosaccharides

Abstract

Amylases of Streptomyces griseus, Pseudomonas stutzeri and Klebsiella pneumoniae produced mainly G₃, G₄ and G₆ at the initial stage of the reaction. The amylase of Bacillus licheniformis had a dual product-specificity for the formation of G₅ and G₃. Amylases of Pseudomonas stutzeri and Bacillus licheniformis catalyzed the degradation of water-insoluble, cross-linked blue starch . All four amylases also hydrolyzed partially-oxidized potato amylose and the degree of hydrolysis increased gradually. The action patterns of four amylases were investigated by two-dimensional paper chromatography by using ¹⁴C-reducing-end-labeled maltooligosaccharides. Three amylases of S. griseus, P. stutzeri, and K pneumoniae were characterized as exo-amylases, and that of B. licheniformis was an endo-amylase. Three such exo-amylases, namely maltotriohydrolase, maltotetraohydrolase, and maltohexaohydrolase formed products having α-configuration . I propose to classify this new group of amylases as “exo-α-amylase” with high product-specificity . Maltohexa ose was also formed from maltotetraose by a transfer reaction of the exo-maltohexaohydrolase, with an action pattern dependent on the substrate concentration. In addition, continuous production of maltotetraose using a dual immobilized enzyme system of maltotetraohydrolase and pullulanase was studied. The effects of operating conditions on the maltotetraose production were examined to confirm that the maltotetraose content of the products could be analyzed using the specific space velocity, SSV. The effectiveness of using immobilized pullulanase along with the maltotetraohydro lase was confirmed from constant-conversion operations in which the maltotetraose content in the product was kept at 50% (w/w) for 60 days in laboratory and bench scale experiments. Furthermore, industrial production and utilization of brand-new starch-related functional oligosaccharides will be described in this paper.