Screening of high-glucoamylase-producing strain of Aspergillus niger with 2-deoxyglucose resistance and the industrial application

Abstract:

[Objective] To obtain mutants of Aspergillus niger with high glucoamylase activity, we developed a screening method. [Methods] We mutagenized the starting strain A. niger X1 using diethyl sulfate, then cultured the mutant library on agar plate containing 2-deoxyglucose. By increasing the concentration of 2-deoxyglucose, we obtained mutants with high resistance to 2-deoxyglucose and then studied glucoamylase activities. [Results] In shake flask fermentation, glucoamylase activity of the mutant strain A. niger DG36 increased by 22.2% to 33.8%. In a 50 m³ fermenter, glucoamylase activity of the strain DG36 reached up to 49094 U/mL at 128 h, 32.8% higher than that of the starting strain A. niger X1. As a result, the fermentation period of the strain DG36 was reduced by 16.9% compared with A. niger X1. [Conclusion] Mutant strain DG36 exhibited higher glucoamylase activity, shorter fermentation period and more suitable for the purification treatment than the starting strain A. niger X1.