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A novel saccharifying α‐amylase of Antarctic psychrotolerant fungi Geomyces pannorum : Gene cloning, functional expression, and characterization
Author(s) -
Gao Bei,
Mao Youzhi,
Zhang Lujia,
He Lei,
Wei Dongzhi
Publication year - 2016
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.201500077
Subject(s) - amylase , thermophile , pichia pastoris , biochemistry , maltose , biology , enzyme , starch , homology (biology) , gene , hydrolysis , recombinant dna
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.