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

• Published in: Starch - Stärke
• Main Authors: Gao, Bei, Mao, Youzhi, Zhang, Lujia, He, Lei, Wei, Dongzhi
• Other Authors: National Natural Foundation of China, Fundamental Research Funds for the Central Universities, National High Technology Research and Development Program of China
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: http://dx.doi.org/10.1002/star.201500077; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fstar.201500077; https://onlinelibrary.wiley.com/doi/pdf/10.1002/star.201500077

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.