产苯丙氨酸解氨酶重组大肠杆菌的培养

The Culture of Recombinant Escherichia coli Producing Phenylalanine Ammonia Lyase

L-苯丙氨酸是人体8种必需氨基酸之一。酶法转化是目前生产L-苯丙氨酸的主要方法。为了提高苯丙氨酸解氨酶的产量,对可高效表达苯丙氨酸解氨酶基因的重组大肠杆菌JM105进行培养,对发酵过程中pH值对工程菌生长的影响进行了研究。结果表明,摇瓶培养条件下,控制发酵过程中发酵液的pH值可显著提高菌体产量,当控制pH值为7.0左右时,菌体量比对照高87%。在初始pH值为7.5的情况下,培养10h后将培养液pH值分别调整为5.5、6.0、6.5、7.0、7.5和8.0,则以pH值为7.5时的菌体量最高。10L发酵罐中控制发酵液pH值为7.5,菌体密度可达A600=20mol/L(DCW=11g/L),比不控制pH值高出33%。试验结果为进一步开展该工程菌的高密度培养提供了一定的参考。

L-phenylalanine （L-phe） is one of eight necessary amino acids in human body. Conversion by phenylalanine ammonia lyase （PLA）is the primary way to produce L-phe. In order to increase the yield of PLA,a recombined Escherichia coli strain JM105 was cultured and the effect of pH values of medium on the growth of this strain was studies. The results show that in the shake flask,biomass of recombined E. coli increases obviously by controlling the pH value of medium. When the medium pH value is maintained around the point of 7.0,the biomass of E.coli is 87% higher than that of the control. When the initial pH is 7.5,after 10 hours＇culture,the medium pH value is adjusted to 5.5,6.0,6.5,7.0,7.5 and 8.0 respectively,and the highest biomass of E.coli is obtained under the pH value of 7.5. In the 10 L fermentor,biomass of E.coli A600 reaches 20 mol/L（DCW=11 g/L）when pH of medium is maintained around 7.5,which is 33% higher than that of the control. The test results provide the reference to the higher density culture of this recombined bacterium.