L-Phenylalanine production from Escherichia coli containing heterologous gene encoding phenylalanine dehydrogenase and formate dehydrogenase

Our research group successfully cloned phenylalanine dehydrogenase from Bacillus badius BC1 into Escherichia coli JM109 by using pUC18 vector. To enhance the enzyme activity and regenerate NAD[superscript +] in a single cell, heterologous genes of phenylalanine dehydrogenase gene (phedh) and formate dehydrogenase gene (fdh) in a high expression vector pET-17b (pETPF and pETFP) were cloned into two kinds of host cell, E. coli BL21(DE3) and E. coli BL21(DE3)pLysS. The heterologous gene expression clones had higher phenylalanine dehydrogenase and formate dehydrogenase activities than those of their original clones (pUCPheDH and pUCFDH). Moreover, their activities were not different from those of their single gene clones (pETPheDH and pETFDH). For phenylalanine production, both of heterologous gene clones could produce optically pure L-phenylalanine 2 times higher than pETPheDH clone. Type of host cell had no effect on phenylalanine production. In addition, phenylalanine production was increased in the range of 14-30% upon the incubation of recombinant cells with hexane for 5 minutes.