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Published on: March 15, 2012
Transporter Engineering for Enhancing Citric Acid Production in Aspergillus niger
Jie Li1, Mingyang Li1, Yan Song1
1Key Laboratory of Industrial Microbiology & Engineering Research Center of Food Biotechnology of Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China.
Journal of Fungi (Basel, Switzerland)
|July 27, 2026
Summary
Engineering the glucose transporter MstF and citrate exporter CexA in Aspergillus niger significantly boosted citric acid production. Simultaneous transporter engineering balanced import and export, enhancing industrial organic acid manufacturing.
Area of Science:
- Biotechnology
- Metabolic Engineering
- Industrial Microbiology
Background:
- Efficient citric acid production by Aspergillus niger is hindered by limitations in substrate uptake and citrate export.
- Optimizing these transport processes is crucial for enhancing citrate synthesis efficiency in industrial settings.
Purpose of the Study:
- To engineer the glucose transporter MstF and citrate exporter CexA in Aspergillus niger to overcome substrate uptake and citrate export limitations.
- To improve overall citric acid production efficiency using a "push-pull" transporter engineering strategy.
Main Methods:
- Genetic modification of Aspergillus niger to overexpress the high-affinity glucose transporter MstF.
- Engineering the citrate exporter CexA to enhance citrate secretion.
- Implementing a "push-pull" strategy involving simultaneous overexpression of both MstF and CexA.
Main Results:
- Single overexpression of mstF in the H7 strain increased citric acid production to 179.35 g/L.
- High expression of cexA alone negatively impacted mycelial formation and gene expression, reducing citric acid yield.
- Simultaneous overexpression of mstF and cexA in strain A5 resulted in a citric acid titer of 185.91 g/L, productivity of 3.21 g/h/L, and a shorter fermentation cycle.
Conclusions:
- Balancing intracellular citrate accumulation and secretion through transporter engineering is key to maximizing citric acid yield.
- The developed "push-pull" strategy offers a viable reference for the industrial production of citric acid and other organic acids.
- Metabolic engineering of transport systems provides an effective approach for enhancing microbial fermentation processes.
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