(274d) Rational Design Of The Most Efficient Utilization Of Hexoses And Pentoses By Escherichia Coli

We have previously applied elementary mode analysis to rationally design the most efficient biomass producing E. coli bacterium which functions according to the pathway with highest yield (Carlson et al, 2004). The strain was constructed and characterized in chemostat studies under completely aerobic growth conditions. The results confirmed that the designed strain achieves a biomass yield on glucose close to the predicted theoretical value which is about 30% higher than the wild type yield under identical growth conditions (Trinh et al., 2006). To make the strain more robust and less sensitive to variations in oxygen supply we have disrupted also the acetate pathways by implementing two additional knockout mutations. This further improves the strain performance under aerobic conditions. Moreover, the set of mutations enhances byproduct formation under anaerobic growth conditions which is also predicted by the theoretical analysis. We have characterized the growth properties of this strain not only with glucose as a carbon source but also with a variety of different pentoses and hexoses. In all cases, the designed strain achieved under aerobic growth conditions a higher biomass yield as compared with the wild type strain or with several industrial E. coli strains under identical growth conditions. The efficient utilization of hexoses and pentoses makes the designed strain not only an efficient host for biotechnological applications such as protein production but also for biofuel production under anaerobic growth conditions.

Carlson et al. (2004) Bioeng. Biotechnol, 85:1-18. Trinh et al. (2006) Metabol. Eng, 8:628-638.