Over-production of β-carotene from metabolically engineered Escherichia coli

To produce recombinant β-carotene in vitro, synthetic operons encoding genes governing its biosynthesis were engineered into Escherichia coli. Constructs harboring these operons were introduced into either a high-copy or low-copy cloning vector. β-Carotene production from these recombinant E. coli cells was either constitutive or inducible depending upon plasmid copy number. The most efficient β-carotene production was with the low-copy based vector. The process was increased incrementally from a 5 l to a 50 l fermentor and finally into a 300 l fermentor. The maximal β-carotene yields achieved using the 50 l and 300 l fermentor were 390 mg l−1 and 240 mg l−1, respectively, with overall productivities of 7.8 mg l−1 h−1 and 4.8 mg l−1 h−1.