摘要：
L-天冬氨酸作为一种大宗氨基酸产品,在医药、食品和化工等方面有着广泛的用途.笔者所在实验室成员前期已经构建1株含有顺丁烯二酸异构酶与L-天冬氨酸氨基裂解酶、且可直接将顺丁烯二酸铵转化成L-天冬氨酸铵的工程菌,对其培养基、发酵条件以及制备条件进行优化.得到的优化发酵培养基:蛋白胨20 g/L,酵母浸粉 5 g/L,NaCl 1.45 g/L,富马酸10 g/L, NH4NO3 8 g/L,乳糖6 g/L,氨水调节pH至7.5.最佳发酵培养条件:发酵罐的转速150 r/min,通气量1.5 L/min,最佳的接种量0.5%(体积分数).通过发酵罐对优化后的培养基进行扩大培养,得出1 L发酵液可以转化1 kg顺丁烯二酸铵,优化后相同培养体积的菌体转化的底物量提高了1倍.为实现"一锅双酶"法制备L-天冬氨酸工艺的规模放大奠定了基础.%L-aspartic acid has been widely used in medicine,food and chemical industries.It is currently produced by a chemoenzymatic process at industrial scale.We have developed a "one-pot two-enzyme" process for the production of L-aspartic acid,which involves a maleate cis-trans isomerase and an l-aspartic acid amino lyase that are highly co-expressed in Escherichia coli.The fermentation conditions were optimized by orthogonal experimental design to improve the enzyme production.The optimum medium composition was as follows (g/L):tryptone 20,yeast extract 5,NaCl 5,fumaric acid 10,NH4NO3 8,lactose 6,and pH 7.5.The optimum conditions were as follow:rotational speed 150 r/min,ventilation 1.5 L/min,inoculum concentration 0.5%.The enzyme activity was two times higher than that before optimization,thus enabling the scale-up of the process to ensure the production of l-aspartic acid at industrial scale by this "one-pot two-enzyme" process.
