L-赖氨酸高产基因工程菌的构建

赖氨酸的高产菌株已通过经典的诱变法获得,但要再提高这些诱变株的产量就很困难.赖氨酸的生物合成很有规律,它不仅依赖于赖氨酸合成途径中的酶,而且依赖于驱动合成赖氨酸的碳源代谢的酶.为了提高赖氨酸产率,就要求改变碳源的供应,从而控制中间物向赖氨酸合成的转化.二氨基庚二酸合酶基因(dapA)和磷酸烯醇式丙酮酸羧化酶基因(ppc)是菌体在赖氨酸合成代谢途径中,控制表达二氨基庚二酸合酶和磷酸烯醇式丙酮酸羧化酶的关键基因.我们首先分别克隆这两个基因,并使之处于一定启动子控制下.然后将dapA和ppc重组克隆到同一个载体,并转化赖氨酸发酵菌,从而提高菌体内的酶活,进一步提高赖氨酸发酵产率.

Constraction of High Product Gene-engineering Strains of L-lgsine

The strains induced by normal method process high product in lysine,but this product can't be increased any more.Biosynthesis of lysine is regular,it depends on not only synthesis enzyme but also invert enzyme,thus medium produce is easy to be translated into lysine. dapA and ppc are the key genes in the path of lysine-biosynthesis. We cloned these two genes and controled them under promotor.Then we cloned dapA and ppc in one vector,transferred Flavum brevibacteria,increased enzyme activity in bacteria,and in final inceased yield of lysine.