Synergistic effects of multiple enzymes from industrial Aspergillus niger strain O1 on starch saccharification

Wenzhu Guo,Wenliang Sun,Chaoguang Tian,Qian Liu,Dandan Liu,Xingji Wang,Tianchen Huang,Leilei Zhu,Jingen Li,Jianhua Yang

doi:10.1186/s13068-021-02074-x

Abstract

BackgroundStarch is one of the most important renewable polysaccharides in nature for production of bio-ethanol. The starch saccharification step facilitates the depolymerization of starch to yield glucose for biofuels production. The filamentous fungus Aspergillus niger (A. niger) is the most used microbial cell factory for production of the commercial glucoamylase. However, the role of each component in glucoamylases cocktail of A. niger O1 for starch saccharification remains unclear except glucoamylase.ResultsIn this study, we identified the key enzymes contributing to the starch saccharification process are glucoamylase, α-amylase and acid α-amylase out of 29 glycoside hydrolases from the 6-day fermentation products of A. niger O1. Through the synergistic study of the multienzymes for the starch saccharification in vitro, we found that increasing the amount of α-amylase by 5-10 times enhanced the efficiency of starch saccharification by 14.2-23.2%. Overexpression of acid α-amylase in strain O1 in vivo increased the total glucoamylase activity of O1 cultures by 15.0%.ConclusionsOur study clarifies the synergistic effects among the components of glucoamylases cocktail, and provides an effective approach to optimize the profile of saccharifying enzymes of strain O1 for improving the total glucoamylase activity.

Highlights

Starch is one of the most important renewable polysaccharides in nature for production of bio-ethanol
Amylose is a linear chain of α-glucose linked by α-1,4-glycosidic linkages, while amylopectin is a branched macromolecule linked by α-1,4-glycosidic linkages and α-1,6-glycosidic linkages [4,5,6]
Amylolytic enzymes that hydrolyze the glycosidic linkages in α-glucans belong to three glycoside hydrolases (GHs) families: GH13 (α-amylases), GH14 (β-amylases) and GH15 [5, 13, 14]. α-Amylases and glucoamylases are widely used in starch conversion [15]. α-Amylases can randomly cleave the internal α-1,4-glycosidic linkages in starch to generate maltose and malto-oligosaccharides

Summary

Introduction

Starch is one of the most important renewable polysaccharides in nature for production of bio-ethanol. The filamentous fungus Aspergillus niger (A. niger) is the most used microbial cell factory for production of the commercial glucoamylase. Starch is one of the most important renewable polysaccharides for the production of bio-ethanol [1, 2]. Starch is composed of two α-glucan polymers, amylose and amylopectin [3]. The filamentous fungus A. niger is used as microbial cell factory for production of lignocellulolytic enzymes and amylolytic enzymes [9,10,11,12]. Amylolytic enzymes that hydrolyze the glycosidic linkages in α-glucans belong to three glycoside hydrolases (GHs) families: GH13 (α-amylases), GH14 (β-amylases) and GH15 (glucoamylases) [5, 13, 14]. Amylolytic enzymes that hydrolyze the glycosidic linkages in α-glucans belong to three glycoside hydrolases (GHs) families: GH13 (α-amylases), GH14 (β-amylases) and GH15 (glucoamylases) [5, 13, 14]. α-Amylases and glucoamylases are widely used in starch conversion [15]. α-Amylases can randomly cleave the internal α-1,4-glycosidic linkages in starch to generate maltose and malto-oligosaccharides

Methods

Results

Conclusion