The goal of the present study was toinve
stigate the effect of different glucose feeding strategies
(batch and fed-batch) on the pDNA productivity of GALG20, a pgi Escherichia coli strain potentially useful in industrial fermentations, which usesthe pentose phosphate pathway (PPP) as the main route for glucose metabolism. The parental strain,MG1655endArecA, and the common laboratory strain, DH5, were used for comparison purposesand pVAX1GFP, a ColE1-type plasmid, was tested as a model. GALG20 produced 3-fold more pDNA(∼141 mg/L) than MG1655endArecA (∼48 mg/L) and DH5 (∼40 mg/L) in glucose-based fed-batchfermentations. The amount of pDNA in lysates obtained from these cells was also larger for GALG20(41%) when compared with MG1655endArecA (31%) and DH5 (26%). However, the final quality ofpDNA preparations obtained with a process that explores precipitation, hydrophobic interaction chro-matography and size exclusion was not significantly affected by strain genotype. Finally, high cell densityfed-batch cultures were performed with GALG20, this time using another ColE1-type plasmid, NTC7482-41H-HA, in pre-industrial facilities using glucose and glycerol. These experiments demonstrated theability of GALG20 to produce high pDNA yields of the order of 2100–2200 mg/L.