Quiescent E. coli as a cell factory

• Main Author: Chen, C.-C.
• Published: University of Cambridge 2010
• Subjects: 572.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597551

The desirability of uncoupling biomass production from product expression stimulated the development of the quiescent cell expression system (Q-cells), a novel bacterial cell factory for the expression of recombinant proteins in non-growing <i>E. coli.</i> This study has confirmed that quiescence can be established in W3110<i>hns</i>-<i>205</i>::Tn<i>10 </i>by adding 3 mM indole to the growth medium. A genetically stable host strain (W3110<i>hns</i>Δ93) has been constructed and found to respond similarly to indole addition. The quiescent cells maintain their protein synthetic capacity and are capable of expressing enhanced green fluorescent protein (EGFP) in shake-flask culture with specific productivities 2- or 3-fold greater than that of a conventional culture. Preliminary investigations have shown that the indole-induced Q-Cell system is capable of scale-up to larger volumes and high density (OD₆₀₀ = 43) in a fed-batch fermentor, where a high specific product formation rate is maintained for an extended period in non-growing cells. It has also been shown that some indole-related compounds can be used to generate productive Q-cells with improved characteristics for recombinant protein synthesis. The results suggest that indole-induced Q-cells constitute a viable cell factory with considerable improvements over the original Rcd-based system and may have considerable potential for the production of recombinant proteins and a wide range of metabolites on both small and large scales.