A novel cold-adapted type I pullulanase of Paenibacillus polymyxa Nws-pp2: in vivo functional expression and biochemical characterization of glucans hydrolyzates analysis

摘要

BackgroundPullulanase is an important debranching enzyme and has been widely utilized to hydrolyse the α-1,6 glucosidic linkages in starch/sugar industry. Selecting new bacterial strains or improving bacterial strains is a prerequisite and effective solution in industrial applications. Although many pullulanase genes have been cloned and sequenced, there is no report of P. polymyxa type I pullulanase gene or the recombinant strain. Meanwhile most of the type I pullulanase investigated exhibit thermophilic or mesophilic properties. There are just few reports of cold-adapted pullulanases, which have optimum activity at moderate temperature and exhibit rather high catalytic activity at cold. Previously, six strains showing distinct pullulan degradation ability were isolated using enrichment procedures. As containing novel bacterium resource and significant pullulanase activity, strain Nws-pp2 was selected for in-depth study.