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Liu J, Zhang Q, Liang X, Zhang R, Huang X, Zhang S, Xie Z, Gao W, Liu H. Improving glucose oxidase catalysis in Aspergillus niger via Vitreoscilla hemoglobin fusion protein. Appl Microbiol Biotechnol 2024; 108:48. [PMID: 38183481 DOI: 10.1007/s00253-023-12931-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 10/17/2023] [Accepted: 10/27/2023] [Indexed: 01/08/2024]
Abstract
Oxygen is crucial for converting glucose to gluconic acid catalyzed by glucose oxidase (Gox). However, industrial gluconic acid production faces oxygen supply limitations. To enhance Gox efficiency, Vitreoscilla hemoglobin (VHb) has been considered as an efficient oxygen transfer carrier. This study identified GoxA, a specific isoform of Gox in the industrial gluconic acid-producing strain of Aspergillus niger. Various forms of VHb expression in A. niger were tested to improve GoxA's catalytic efficiency. Surprisingly, the expression of free VHb, both intracellularly and extracellularly, did not promote gluconic acid production during shake flask fermentation. Then, five fusion proteins were constructed by linking Gox and VHb using various methods. Among these, VHb-GS1-GoxA, where VHb's C-terminus connected to GoxA's N-terminus via the flexible linker GS1, demonstrated a significantly higher Kcat/Km value (96% higher) than GoxA. Unfortunately, the expression of VHb-GS1-GoxA in A. niger was limited, resulting in a low gluconic acid production of 3.0 g/L. To overcome the low expression problem, single- and dual-strain systems were designed with tools of SpyCatcher/SpyTag and SnoopCatcher/SnoopTag. In these systems, Gox and VHb were separately expressed and then self-assembled into complex proteins. Impressively, the single-strain system outperformed the GoxA overexpression strain S1971, resulting in 23% and 9% higher gluconic acid production under 0.6 vvm and 1.2 vvm aeration conditions in the bioreactor fermentation, respectively. The successful construction of Gox and VHb fusion or complex proteins, as proposed in this study, presents promising approaches to enhance Gox catalytic efficiency and lower aerodynamic costs in gluconic acid production. KEY POINTS: • Overexpressing free VHb in A. niger did not improve the catalytic efficiency of Gox • The VHb-GS1-GoxA showed an increased Kcat/Km value by 96% than GoxA • The single-strain system worked better in the gluconic acid bioreactor fermentation.
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Affiliation(s)
- Jiao Liu
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China
- Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, Tianjin University of Science & Technology, Tianjin, 300457, China
| | - Qian Zhang
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China
| | - Xingying Liang
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China
| | - Rong Zhang
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China
| | - Xiaojie Huang
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China
- Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, Tianjin University of Science & Technology, Tianjin, 300457, China
| | - Shanshan Zhang
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China
- Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, Tianjin University of Science & Technology, Tianjin, 300457, China
| | - Zhoujie Xie
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China
- Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, Tianjin University of Science & Technology, Tianjin, 300457, China
| | - Weixia Gao
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China
- Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, Tianjin University of Science & Technology, Tianjin, 300457, China
| | - Hao Liu
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science & Technology, Tianjin, 300457, China.
- Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, Tianjin University of Science & Technology, Tianjin, 300457, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, 300308, People's Republic of China.
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Application of an S-layer protein as a self-aggregating tag for cost-effective separation of recombinant human and yeast D-amino acid oxidases in the aqueous two-phase system. Biotechnol Lett 2019; 42:241-248. [PMID: 31760528 DOI: 10.1007/s10529-019-02768-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 11/19/2019] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To evaluate whether the surface layer (S-layer) protein of Lactobacillus brevis serves as a self-aggregating protein tag for cost-effective separation of human and yeast D-amino acid oxidases (hDAAO and yDAAO) expressed in E. coli. RESULTS In aqueous two-phase (PEG-phosphate) system, the S-layer:DAAO fusion proteins (shDAAO and syDAAO) were separated at the interface with a recovery of 82 ± 10.6% for shDAAO and 95 ± 1.9% for syDAAO. Some shDAAO proteins were separated as precipitates with a recovery of 41 ± 0.5% in phosphate (9%, w/w) using PEG 3000 and PEG 4000 (16%, w/w), while some syDAAO proteins were also isolated as precipitates with a recovery of 75 ± 17.5% in phosphate (9%, w/w) using PEG 4000 and PEG 8000 (16%, w/w). CONCLUSIONS The S-layer of L. brevis was applied to a self-assembled protein tag to enable cost-effective separation of human and yeast D-amino acid oxidases expressed in E. coli cells. Because of the self-assembling properties of S-layer proteins, human and yeast D-amino acid oxidases fused with S-layer proteins could be easily separated by aggregates at the interface and/or in a few conditions by precipitates to the bottom of the PEG-phosphate aqueous system.
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