【摘要】 琥珀酸在食品中有广泛的用途，但琥珀酸发酵往往受制于还原力不平衡的问题。相比于其他常用于平衡还原力的酶，亚磷酸脱氢酶催化产物为磷酸盐，对后续琥珀酸的分离纯化影响较小。文章克隆了来源于施氏假单胞菌的亚磷酸脱氢酶(编码基因为ptxD),比较ptxD在载体和基因组上表达对琥珀酸发酵的影响，同时研究了亚磷酸盐添加量对发酵的影响。结果表明，在ptxD表达条件下，亚磷酸盐在5～15 mmol/L范围内添加并未表现出对细胞生长的抑制性，且在10 mmol/L时展现出较高的糖耗速率和琥珀酸得率。基因组上表达ptxD的工程菌WS105(WS100,iclR::pJ23119-ptxd)能积累79.38 g/L琥珀酸，较载体上表达ptxD的工程菌WS104(WS100/puc19-pJ23119-ptxd)提升了4.87%,较出发菌株WS100提升了13.81%。WS105副产物乙酸含量显著下降，浓度为2.76 g/L,较WS100、WS104分别降低了42.38%、29.41%,表明亚磷酸脱氢酶的表达能有效促进琥珀酸产量的提高。更多还原

【Abstract】 Succinic acid has a wide range of uses in food, but succinic acid fermentation is often limited by the problem of unbalanced reducing power. Compared with other enzymes commonly used for balancing reducing power, the catalytic product of phosphite dehydrogenase is phosphate, which has little effect on the subsequent separation and purification of succinic acid. In this paper, a phosphite dehydrogenase(encoding gene is ptxD) from Pseudomonas schszei is cloned, the effects of ptxD expression in vectors and genomes on succinic acid fermentation are compared, and the effect of phosphite addition amount on fermentation is also studied. The results show that under the condition of ptxD expression, the addition of phosphite within the range of 5～15 mmol/L does not exhibit any inhibitory effect on cell growth, and at 10 mmol/L, it exhibits a higher sugar consumption rate and succinic acid yield. The engineering strain WS105(WS100, iclR::pJ23119-ptxd) expressing ptxD on the genome can accumulate 79.38 g/L succinic acid, which is 4.87% higher than the engineering strain WS104(WS100/puc19-pJ23119-ptxd) expressing ptxD on the vector, and 13.81% higher than that of the starting strain WS100. The content of acetic acid, a by-product of WS105, significantly decreases and the concentration is 2.76 g/L, which is 42.38% and 29.41% lower than WS100 and WS104 respectively, indicating that the expression of phosphite dehydrogenase can effectively promote the increase of succinic acid production.更多还原