Metabolic engineering of Escherichia coli for the production of riboflavin

Table 2 Effect of overexpressing pentose phosphate pathway genes on riboflavin production and enzyme activities

Strain/plasmid	OD600 ^a	Riboflavin (mg/L)	Riboflavin yield (mg/g) ^b	Enzyme activity (nmol/min/mg protein) ^c
Strain/plasmid	OD600 ^a	Riboflavin (mg/L)	Riboflavin yield (mg/g) ^b	G6PDH ^d	6PGDH ^d
RF01S/p15Trc	3.8±0.1	192.1±7.3	23.0±0.9	111.5±11.5	119.1±8.4
RF01S/p15Trc-zg	3.0±0.1	197.4±9.2	24.2±1.4	203.6±18.5	174.7±14.2
RF01S/p15Trc-zgp	3.1±0.1	228.4±0.9	31.9±1.3	199.0±20.0	177.1±17.6

^aOD₆₀₀ is the final optical density of the culture.
^bmg/g: mg/g-consumed glucose.
Batch cultures of recombinant strains were carried out in LB medium containing 10 g/L glucose at 37°C as described in methods. Standard deviations were calculated from the results of three independent experiments.
^cOne unit of the enzyme activity was defined as the amount catalyzing the formation of 1 nmol of NADPH per min. Results are the mean values of three measurements.
^d6PGDH, 6-phosphogluconate dehydrogenase; G6PDH, glucose 6-phosphate dehydrogenase.

ISSN: 1475-2859