Development of a cost-effective medium for submerged production of fungal aryl alcohol oxidase using a genetically modified Aspergillus nidulans strain

• Published in: Bioresource technology 2020-06, Vol.305, p.123038-123038, Article 123038
• Main Authors: Liu, Enshi, Li, Mengxing, Abdella, Asmaa, Wilkins, Mark R.
• Format: Article
• Language: English
• Subjects: Enzyme production; Filamentous fungi; Lignin-degrading enzymes; Medium development; Submerged fermentation
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2020.123038

•Cost-effective medium for AAO production by Aspergillus nidulans was developed.•Corn steep liquor provided sufficient nutrients for enzyme production.•Medium components were optimized and validated.•Greatest aryl alcohol oxidase activity (1021 U/L) was achieved.•Protein concentration reached 0.75 g/L. Aryl alcohol oxidase (AAO), an extracellular H2O2-providing enzyme, plays a central role in lignin depolymerization. Cost-effective production of AAO has not been achieved, due to the low yield of enzyme-producing microorganisms and the high cost of fermentation media. This study aims to develop a cost-effective medium for high-yield production of AAO in submerged culture using a recombinant Aspergillus nidulans strain. Results demonstrate that corn steep liquor (CSL) was a rich but inexpensive nitrogen source for AAO production, and CSL can provide enough trace metals and vitamins (i.e. pyridoxine) for A. nidulans. A 2-level Plackett-Burman design was utilized to determine the main affecting factors in AAO production. The medium was further optimized by a 3-level Box-Behnken design to obtain the optimum medium component concentrations (61.0 g/L maltose, 26.4 g/L CSL, and 13.8 g/L NaNO3). The greatest AAO activity achieved was 1021 U/L with a protein concentration of 0.75 g/L.