LanzaTech and Oak Ridge National Laboratory have developed and scaled up a process for sustainable production of acetone and downstream drop-in fuel and commodity products directly from biomass syngas via a novel energy conserving route in engineered acetogenic bacteria. This process offers a safer and more environmentally-friendly production method for acetone production than the current phenol-dependent method, and the product has significantly lower GHG emissions. The developed process offers a cost competitive route to Acetone and enables biofuels at or below DOE?s $3 gge target. In addition, it also provides an attractive biological alternative to traditional sugar-based ABE fermentation, by enabling utilization of non-food biomass resources as fermentation feedstocks. Challenges overcome: ? By-products formation: Byproduct 2,3-butandiol and 3-hydroxybutyrate reduce yield and stability. Addressed by elimination of both pathways in our chassis acetone production strain. ? Cost competitiveness: Addressed by developing an integrated acetone strain and eliminating by-products to increase yield and stability. Optimized co-selectivity and coproductivity of acetone and ethanol instead of titer, based on technoeconomic analysis. ? Limited enzyme variety: Addressed by genome mining of over 300 industrial strains in LanzaTech collection, identifying unique enzyme sequences, and refactoring these unique enzyme variants through LanzaTech?s engineering platform. Resulted in over 10x improvement in acetone production from gas. ? Continuous process (stability): Identified bottleneck through detailed omics studies, addressed by integration of the acetone pathway on the chromosome. ? Novel process to scale up: Addressed by demonstrating stable acetone production in a 80- L pilot reactor, with acetone productivity and selectivity comparable to those observed under the same conditions in 2-L reactors. We have demonstrated stable acetone production for over 7 days at commercial target rate and selectivity in 2-L reactors and have piloted the process.