Monday, July 25, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
Substrate-selective uptake is a novel approach for the simultaneous consumption of sugars found in biomass hydrolysates. Comparing growth rate of E. coli strains, we observed that wild type E. coli W was generally the best at consuming carbohydrates. The triple-knockout strain W glk, ptsG manZ (KD777) consumed 7 g/L L-arabinose or D-xylose within 5.5 h, and subsequently consumed glucose only slowly. The presence of glucose did affect the utilization of D-galactose by KD777. The presence of pentose effectively hindered glucose metabolism in KD777. Two-sugar carbon-limited chemostats with KD777 at a growth rate of 0.25 h-1 showed that glucose partially replaced xylose, arabinose, galactose consumption. Using strain KD777 in conjunction with another glucose-selective strain would allow xylose, arabinose and glucose to be consumed more quickly than by a single-organism approach. The process will probably hold promise for the conversion of variable sugar feed streams, such as lignocellulosic hydrolysates.