The production of 1,3-propanediol (1,3-PD) from glycerol by Klebsiella pneumoniae is limited by synthesis of numerous byproducts. Among them, the accumulation of acetate has the largest negative impact on the fermentation performance. To address the acetate overflow caused by knocking out lactate dehydrogenase, alcohol dehydrogenase and succinate dehydrogenase, several metabolic engineering manipulations were conducted. First, acetate was reduced through enhancing the acetate assimilation pathway by overexpressing heterologous acetyl-CoA synthetase. Then, the polyhydroxybutyrate (PHB) synthesis pathway was introduced to further reprogram the intracellular carbon metabolism. As a result, the best performed strain Kpr-6 produced up to 91.2 g/L extracellular 1,3-PD and 2.56 g/L intracellular PHB which can be easily separated from each other, while the acetate was dramatically reduced. The metabolic engineering strategies developed in this study would be helpful for constructing the microbial cell factory for other similar bio-based chemical production.

肺炎克雷伯菌由甘油生产1,3-丙二醇（1,3-PD）受许多副产物合成的限制。其中，乙酸盐的积累对发酵性能具有最大的负面影响。为了解决由敲除乳酸脱氢酶，醇脱氢酶和琥珀酸脱氢酶引起的乙酸盐溢出，进行了几种代谢工程操作。首先，通过过表达异源乙酰辅酶A合成酶来增强乙酸酯同化途径来减少乙酸酯。然后，引入多羟基丁酸酯（PHB）合成途径，以进一步重新编程细胞内碳代谢。结果，表现最佳的菌株Kpr-6产生高达91.2 g / L的细胞外1,3-PD和2.56 g / L的细胞内PHB，可以很容易地彼此分离，而乙酸盐则大大减少。