APPLICATIONS OF TECHNOLOGY:
- Production of citramalate, a precursor for polymethyl methacrylate (PMMA) polymers.
- PMMA is used in electronic device screens, automotive plastics, glazing, building piping, and insulation
- Increases the achievable carbon yields of select organic acids
- Consumes less energy and generates less toxic waste than current chemical methods for production of methyl methacrylate (MMA)
MMA is an important building block for production of polymethyl methacrylate (PMMA), an economical alternative to polycarbonate. Currently, MMA is produced from petrochemicals through chemical processes, which consumes a lot of energy and generates toxic waste. A bio-and chemical-hybrid process for MMA production employing citramalate, a precursor molecule to MMA, is an alternative. Citramalate production using non-native pathways in microbes, however, suffers from yield loss due to the production of unwanted byproducts. Therefore, there is a need for strain optimization of citramalate-producing microbes.
Researchers at Berkeley Lab and collaborating institutions have engineered a non-model yeast strain that produces high yields of citramalate via overexpression of citramalate synthase.
Genome-scale metabolic models were used to target citramalate synthase compatible genes in the non-model yeast I. orientalis. This strain has the potential to reduce the cost and environmental footprint of organic acid production compared to model strains such as E. coli and S. cerevisiae. However, current metabolic engineering tools are limited for non-model strains.
After identification of target genes, citramalate synthase was expressed with integration into various chromosomal locations and copy numbers. They achieved production of 4-6 g/L citramalate. Researchers plan to increase strain productivity further by developing a genome integration strategy that stabilizes expression of citramalate synthase.
- Yasuo Yoshikuni
- Zong-Yen Wu
- Ping-Hung Hsieh
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