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Maltooligosaccharide-forming amylases (MFAses) are promising enzymes for a variety of industrial applications. In this study, a maltooligosaccharide-forming amylase (BkAmy) isolated from Bacillus koreensis HL12 was first heterologous expressed and characterized. According to structural-sequence alignment, BkAmy contained seven conserved regions which are the signature of a novel GH13 subfamily. The gene was expressed in Pichia pastoris KM71 as an extracellular protein with a volumetric activity of 3.38 U/mL culture medium after 72 h induction by 3% (w/v) of methanol. The recombinant BkAmy migrated as a single protein band with an expected size approximately of 55 kDa. BkAmy exhibited the highest catalytic activity on soluble starch with a specific activity of 42.2 U/mg at 40 °C, pH 7.0. The enzyme exhibited 65% relative activity at 30 °C, indicating its advantage on application at moderate reaction …