Manipulation of an α-glucosidase in the industrial glucoamylase-producing Aspergillus niger strain O1 to decrease non-fermentable sugars production and increase glucoamylase activity

作者：Wenzhu Guo, Dandan Liu, Jingen Li, Wenliang Sun, Tao Sun, Xingji Wang, Kefen Wang, Qian Liu, Chaoguang Tian · 发表于：Frontiers in Microbiology · 年份：2022 · DOI：10.3389/fmicb.2022.1029361 · 被引用次数：11 · 研究领域：Enzyme Production and Characterization、Biofuel production and bioconversion、Microbial Metabolites in Food Biotechnology

Dextrose equivalent of glucose from starch hydrolysis is a critical index for starch-hydrolysis industry. Improving glucose yield and decreasing the non]-fermentable sugars which caused by transglycosylation activity of the enzymes during the starch saccharification is an important direction. In this study, we identified two key α-glucosidases responsible for producing non-fermentable sugars in an industrial glucoamylase-producing strain Aspergillus niger O1. The results showed the transglycosylation product panose was decreased by more than 88.0% in agdA / agdB double knock-out strains than strain O1. Additionally, the B-P1 domain of agdB was found accountable as starch hydrolysis activity only, and B-P1 overexpression in Δ A Δ B -21 significantly increased glucoamylase activity whereas keeping the glucoamylase cocktail low transglycosylation activity. The total amounts of the transglycosylation products isomaltose and panose were significantly decreased in final strain B-P1-3 by 40.7% and 44.5%, respectively. The application of engineered strains will decrease the cost and add the value of product for starch biorefinery.