Purification and characterization of glucoamylase of Aspergillus oryzae from Luzhou-flavour Daqu.
Biotechnol Lett. 2020 Jul 04;:
Authors: Wang C, Yang L, Luo L, Tang S, Wang Q
OBJECTIVE: To obtain novel glucoamylase from Daqu microbe.
RESULTS: A dominant strain known as LZ2 with high activity of hydrolyzing starch was isolated from Luzhou Daqu, a Chinese traditional fermentation starter. The LZ2 was identified as Aspergillus oryzae by 18S rDNA sequence analysis. Glucoamylase from LZ2, named as GA-LZ2, was purified to homogeneity and showed a single band with expected molecular mass of 60 kD. The GA-LZ2 effectively degraded amylose, rice starch and wheat starch. Optimal temperature and pH value of enzyme were 60 °C and pH 4.0 respectively. The GA-LZ2 displayed significant thermal stability and pH stability at moderate temperature and low pH. Intriguingly, the thermostability was enhanced in the presence of starch. In addition, GA-LZ2 exhibited insensitivity to glucose, independence of metal ions and tolerance to organic solvents. The GA-LZ2 retained complete activity in the presence of 100 mM glucose and 5% ethanol and methanol.
CONCLUSION: Glucoamylase GA-LZ2 displayed broad substrate specificity, strong stability and tolerance, suggesting that GA-LZ2 carry potential for industrial application in bioethanol production.
PMID: 32623532 [PubMed – as supplied by publisher]