ABSTRACT
CGTase (EC 2.4.1.19) is a unique member of the -amylase family. Its main products when acting on starch are cyclodextrins and highly branched high-molecular-weight dextrins (CGTase limit dextrins). CGTase has been identified in bacteria belonging to the genera Bacillus, Clostridium, Klebsiella, Micrococcus, Thermoanaerobacter, and Thermoanaerobacterium (6), and in a single archaeon, Thermococcus (7). CGTase is present as an extracellular enzyme and functions in the initial attack on this polymeric substrate. These bacteria subsequently use the cyclodextrins produced as carbon and energy
sources for growth. This involves a cell-associated cyclomaltodextrinase (EC 3.2.1.54), yielding glucose, maltose, and maltotriose (8). Glucose is metabolized intracellularly via glycolysis.
