Microbial conversion of abundant and sustainable lignocellulosic biomass to biofuels and biochemicals offers the opportunity to reduce dependence on fossil fuels and chemicals. While naturally occurring Zymomonas mobilis has a high specific glucose uptake rate, rapid catabolism, and high ethanol yield, engineered Z. mobilis also can efficiently convert xylose and arabinose plant sugars to ethanol. In pursuit of bio-derived fuel and chemical precursors, researchers at the National Renewable Energy Laboratory have engineered natural Z. mobilis to produce 2,3-butanediol for fuel and chemical applications. Capable of metabolizing the vast majority of biomass sugars in an otherwise toxic hydrolysate environment, Z. mobilis is aptly suited for the efficient conversion of lignocellulosic biomass-hydrolysate sugars to commercially important fuels and chemicals.
Researchers at the National Renewable Energy Laboratory (NREL) have engineered naturally occurring Zymomonas mobilis to produce 2,3-butanediol (2,3-BDO) at high yields and titers in an otherwise toxic environment populated with hydrolysate sugars derived from lignocellulosic biomass. Z. mobilis can produce 2,3-BDO only or 2,3-BDO in combination with ethanol, depending on the particular modification of Z. mobilis’s metabolic pathway. For simultaneous 2,3-BDO and ethanol production, NREL’s researchers introduced exogenous genes on an extrachromosomal plasmid into naturally occurring Z. mobilis for 2,3-BDO synthesis. For only 2,3-BDO production after introduction of the 2,3-BDO synthesis pathway, knockout of the pyruvate-decarboxylase gene deletes the gene that is responsible for ethanol production. The resultant Z. mobilis chimera provides an excellent industrial platform for 2,3-BDO synthesis with no ethanol production, as its efficient catabolism of various biomass sugars and exclusive 2,3-BDO production allows high product titers and a simplified chemical-separation process for 2,3-BDO extraction.
To learn more about Engineered Zymomonas for the Production of 2,3–butanediol, please contact Eric Payne at:
U.S. Patent Application US 2019/0,153,483 A1
Applications and Industries
- Biofuels such as diesel, jet fuel, and kerosene,
- Fuel additives,
- Organic solvents,
- Chemicals or chemical intermediates
NREL's Z. mobilis chimera in an otherwise toxic lignocellulosic biomass-hydrolysate environment provides:
- Direct conversion pathways from hydrolysate sugars to 2,3-butanediol,
- Efficient catabolism of hydrolysate sugars for high 2,3-butanediol yields and titers,
- Optional co-production of ethanol with 2,3-butanediol,
- Exclusive 2,3-butanediol synthesis, and
- Simplified product-extraction procedures.