A novel saccharifying α‐amylase of Antarctic psychrotolerant fungi Geomyces pannorum : Gene cloning, functional expression, and characterization

A DNA segment encoding a novel α‐amylase was cloned from the Antarctic psychrotolerant fungi Geomyces pannorum . The gene has an open reading frame of 1761 bp, deduced 586 amino acids, revealing a relatively low homology to α‐amylases from diverse fungal genera. The α‐amylase gene was overexpressed in Pichia pastoris , and the recombinant α‐amylase was purified and characterized. Enzymatic activity was optimal at pH 6.0 and 70°C, and the specific activity was 9.78 × 10 3  U/mg when using soluble starch as substrate. Moreover, the enzyme retained more than 90% of its maximum activity over a wide pH range (6.0–9.0). Exceptionally, the main hydrolysis products of soluble starch catalyzed by the enzyme were glucose and maltose, of which glucose reached a concentration of 68.8% (w/w). This is the first report on identifying thermophilic fungal amylase from psychrotolerant fungi. Also, the preliminary study on the high‐glucose‐producing α‐amylase with detailed enzymatic properties shows a potential application prospect in syrup industry.