Development of an Inosine Hyperproducer from Bacillus licheniformis by Systems Metabolic Engineering
Menglin Zhou1, Yi Li1, Youhua Cai2
1State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, College of Life Sciences, Hubei University, Wuhan 430062, PR China.
Journal of Agricultural and Food Chemistry
|December 11, 2023
Summary
This study engineered Bacillus licheniformis to produce high levels of inosine, a compound vital for food, chemical, and medicine industries. Metabolic engineering strategies significantly boosted inosine production, achieving a final titer of 27.41 g/L.
Area of Science:
- Microbiology
- Metabolic Engineering
- Biotechnology
Background:
- Inosine is a crucial compound with applications in the food, chemical, and pharmaceutical industries.
- Efficient microbial production of inosine is essential for meeting industrial demands.
Purpose of the Study:
- To develop a hyperproducing strain of *Bacillus licheniformis* for inosine synthesis using systems metabolic engineering.
- To optimize metabolic pathways for enhanced inosine yield and productivity.
Main Methods:
- Genetic modifications in *Bacillus licheniformis* including deletion of inhibitor genes (PurR, YabJ) and overexpression of the *pur* operon.
- Optimization of 5-phosphoribosyl-1-pyrophosphate (PRPP) supply via glucose transport and pentose phosphate pathway engineering.
- Deletion of genes involved in inosine degradation (*deoD*, *pupG*) and downregulation of adenosine 5'-monophosphate (AMP) synthesis.
- Enhancement of glycine and aspartate supply, and blockage of the guanosine synthesis pathway.
Main Results:
- Activation of purine metabolism and PRPP supply increased inosine titer by 97% and reduced byproducts by 36%.
- Deletion of degradation genes led to 0.91 g/L inosine accumulation.
- Downregulation of AMP synthesis and enhancement of amino acid supply further boosted inosine titers by 409% and 298%, respectively.
- The engineered strain IR-8-2 achieved a final inosine titer of 27.41 g/L, with a yield of 0.46 g/g glucose and productivity of 0.38 g/(L·h).
Conclusions:
- Systems metabolic engineering effectively created an inosine hyperproducer strain of *Bacillus licheniformis*.
- The study demonstrates a multi-pronged approach to metabolic pathway optimization for high-titer microbial production of inosine.
- The developed strain holds significant potential for industrial-scale inosine manufacturing.
