Fed batch culture with declining specific growth rate for high-yielding production of a plasmid containing a gene therapy sequence in Escherichia coli DH1

Large‐scale production of endotoxin‐free plasmids for transient expression in mammalian cell culture

“…It is in the agreement with literature describing inverse relation of the plasmid content and growth rate (O'Kennedy et al, 2003) and transient increase of specific plasmid yield after transition from batch culture to chemostat (Rozkov et al, 2006). The specific plasmid yield was also increasing during fed-batch culture with constant feeding rate and gradually declining specific growth rate (Listner et al, 2006;Rozkov et al, 2006). Restriction of the growth rate to 0.12 h À1 in fed-batch culture and temperature induction was reported to increase volumetric plasmid yield to 1.5 g L À1 (Carnes et al, 2006).…”

“…Minimal medium can be easily adapted for fed-batch culture to achieve even higher cell densities by supplying glucose at a limiting rate thus avoiding oxygen limitation and acetate accumulation (Paalme et al, 1990). Examples where fed-batch was applied for plasmid production include a culture with DOT-controlled feed and semi-defined medium where cell density reached 60 g L À1 DW (about 270 g L À1 WW) (Chen et al, 1997) and fed-batch culture with constant feed rate with the final cell density 35 g L À1 DW (160 g L À1 WW; Rozkov et al, 2006). Another way to achieve a higher volumetric yield of plasmid is by increasing the specific yield, which depends not only on the vector, but also on culture medium and cultivation conditions.…”

“…The aeration rate was 2.5 L min À1 , overpressure 0.1 bar. The minimal medium was based on previously published recipe (Rozkov et al, 2006) with minor modifications:…”

DNA plasmid production in different host strains of Escherichia coli

“…Recent work on DNA plasmid production generally has focused on maximizing yield, and most studies have examined only a very few variables, for example, medium components [31,51] or slight changes in growth rate [7,36]. The cost in manpower, materials and time associated with commercial-scale processes encourages the development of a small-scale screening protocol for candidate strains and fermentation conditions.…”

“…For example, [7] observed a Wvefold greater speciWc yield in a DO-stat, nutrient-limited fed-batch process ( = 0.13 h ¡1 ) compared to non-limiting process ( = 0.5-1.0 h ¡1 ). Similarly, 70% greater speciWc yield was observed during the late growth phase ( = 0.1 h ¡1 ) compared to the early growth phase ( = 0.48 h ¡1 ) during a linear-feeding process [36].…”