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Updated: Feb 26, 2026

Optimization and Utilization of Agrobacterium-mediated Transient Protein Production in Nicotiana
Published on: April 19, 2014
Promoting nitrogen fixation by threonine synthesis in co-culture of Azotobacter vinelandii and Escherichia coli
Yingchen Wang1, Wangyin Wang2, Wenhui Sun2
1State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Abstract:
Amino acid production directly from N2 is a big challenge in green biomanufacturing. Merging biological nitrogen fixation (BNF) with target amino acid biosynthesis in co-culture system offers a promising solution. Here, we constructed a Nitrogen Fixation-Utilization Coupling (NFUC) system that enabled threonine production directly from N2 and ethanol, by co-culturing engineered Azotobacter vinelandii for BNF and Escherichia coli for threonine biosynthesis. Systematic metabolic engineering increased threonine titer 3.4-fold over the initial co-culture through optimizing NH4+ release, threonine pathway and energy supply. The nitrogen fixation activity of Azotobacter vinelandii was enhanced in co-culture by the demand for threonine synthesis, resulting in an improvement in total fixed nitrogen compared to its monoculture. The observed downregulation of glutamine synthetase activity in co-cultured Azotobacter vinelandii revealed its prioritization of N2 fixation over endogenous amino acid synthesis, enhancing NH4+ availability for Escherichia coli with an increase in extracellular NH4+ level. This NFUC system establishes a platform for sustainable bioproduction of amino acids directly from N2.
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