Core Viewpoint - The article discusses the sustainable production of 1,4-butanediol (BDO) through engineered Escherichia coli, highlighting the potential for antibiotic-free fermentation methods and the optimization of metabolic pathways to enhance yield and efficiency [2][4][20]. Summary by Sections Introduction - 1,4-butanediol (BDO) is a significant non-natural chemical widely used in biodegradable plastics, with a substantial market potential. Traditional production relies on petrochemical methods, while biotechnological approaches face challenges such as low enzyme activity and high production costs [2][4]. Research Content - The study systematically optimized the E. coli chassis by integrating multiple copies of BDO synthesis genes, knocking out byproduct pathways, and engineering key enzymes to enhance metabolic flux. The introduction of a microaerobic fermentation strategy allowed for high BDO yields without antibiotics or inducers [4][5]. Metabolic Engineering Strategies - The research involved various strategies to improve BDO production, including: - Introducing external enzymes and optimizing gene expression to enhance BDO synthesis [7][11]. - Modifying the TCA cycle and enhancing ATP levels to redirect carbon flux towards BDO production [15][18]. - Utilizing the hok/sok system to maintain plasmid stability, achieving a low plasmid loss rate of 5.5% [18][19]. Production Results - In shake flask experiments, BDO production reached 7.88 g/L, the highest reported yield under similar conditions. In a 5-liter bioreactor, BDO production achieved 34.63 g/L with a glucose yield of 0.35 g/g and a production rate of 0.48 g/L/h [20][21]. Conclusion - The study demonstrates a comprehensive metabolic engineering approach for the sustainable industrial production of BDO from glucose, showcasing the potential for antibiotic-free processes and the need for further optimization to address byproduct accumulation [20][22].