Metabolic engineering in Brevibacterium flavum with five key enzyme genes of Escherichia coli for phenylalanine production

摘要

Five genes, ppsA, pckA, aroG, pheA. and tyrB, encoded six key enzymes in the pathway of phenylalanine biosynthesis. In the work, they were amplified from genomic DNA of E. coli mutants by polymerase chain reaction, and inserted into the plasmids p λ P_R or pCZ in different tandem arrangements. Then the constructed plasmids were introduced into Brevibacteriumflavum for gene expression and phenylalanine production. The results showed co-expression of five genes elevate the relevant enzyme activities in the pathway of phenylalanine biosynthesis. A recombinant strain B. flavum 311/pCZ-GAB-2P harboring the five genes was able to increase 3.4-fold in phenylalanine yield relative to that of the host strain in fermentation medium.