Efficient Acetoin Production in Bacillus subtilis by Multivariate Modular Metabolic Engineering with Spatiotemporal Modulation

Acetoin, a promising bio-based platform chemical, is mainly produced through chemical synthesis. Given the increasing attention to nonrenewable resources, developing safe and efficient microbial technologies for acetoin production is necessary. This study redirected more carbon flux to acetoin synthesis by deleting nonessential functional genes in Bacillus subtilis. Subsequently, based on spatial modulation engineering, the biological regulatory elements and DNA scaffold were used to enhance the co-catalytic capacity of key enzymes in the acetoin synthesis pathway. To increase the level of reducing the power of cells in the specific period, the logic gate circuit was built to regulate intracellular cofactor levels and metabolic fluxes distribution. Moreover, through fed-batch fermentation at a 5 L fermenter scale, the maximum acetoin titer achieved was 97.5 g/L, with a production rate of 1.81 g/L/h. To our knowledge, this is the highest acetoin fermentation titer reported for B. subtilis. This study significantly enhanced acetoin production in B. subtilis, offering new insights for the industrial production of bio-based platform chemicals and demonstrating broad application potential.